Calcific uremic arteriolopathy

Abstract

Calcific uremic arteriolopathy (CUA)/calciphylaxis is an important cause of morbidity and mortality in patients with chronic kidney disease requiring renal replacement. Once thought to be rare, it is being increasingly recognized and reported on a global scale. The uremic milieu predisposes to multiple metabolic toxicities including increased levels of reactive oxygen species and inflammation. Increased oxidative stress and inflammation promote this arteriolopathy by adversely affecting endothelial function resulting in a prothrombotic milieu and significant remodeling effects on vascular smooth muscle cells. These arteriolar pathological effects include intimal hyperplasia, inflammation, endovascular fibrosis and vascular smooth muscle cell apoptosis and differentiation into bone forming osteoblast-like cells resulting in medial calcification. Systemic factors promoting this vascular condition include elevated calcium, parathyroid hormone and hyperphosphatemia with consequent increases in the calcium × phosphate product. The uremic milieu contributes to a marked increased in upstream reactive oxygen species—oxidative stress and subsequent downstream increased inflammation, in part, via activation of the nuclear transcription factor NFκB and associated downstream cytokine pathways. Consitutive anti-calcification proteins such as Fetuin-A and matrix GLA proteins and their signaling pathways may be decreased, which further contributes to medial vascular calcification. The resulting clinical entity is painful, debilitating and contributes to the excess morbidity and mortality associated with chronic kidney disease and end stage renal disease. These same histopathologic conditions also occur in patients without uremia and therefore, the term calcific obliterative arteriolopathy could be utilized in these conditions.

Full text

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 109
Oxidative Medicine and Cellular Longevity 3:2, 109-121; March/April 2010; © 2010 Landes Bioscience
REVIEW
REVIEW
*Correspondence to: Melvin R . Hayden; Email: mrh29@usmo.com
Submitted: 01/21/10; Revised: 01/29/10; Accepted: 02/01/10
Previously published online:
www.landesbioscience.com/journals/oximed/article/11354
Introduction
Calcific uremic arteriolopathy (CUA), previously termed calci-
phylaxis, characteristically occurs in patients with chronic kid-
ney disease (CKD), especially those nearing or at end stage renal
disease (ESRD) with secondary hyperparathyroidism.1 However,
CUA has been observed in patients with normal renal function
and calcium/phosphate metabolism.2-4 Its etiology is multifacto-
rial and its estimated prevalence is reported in up to 4% of patients
on dialysis.5,6 Risk factors are multiple and include female gender,
diabetes mellitus, hyperphosphatemia, CKD, ESRD, mineral
and bone disorders, obesity, warfarin anticoagulation, Caucasian
ethnicity and others (Table 1).6-14
The term calciphylaxis was originally coined by Hans Seyle
in 1962.15 In this context, he created a rodent model of systemic
and local soft-tissue calcification characterized by sensitizing fac-
tors such as parathyroid hormone, vitamin D or a diet high in
calcium and phosphorus followed by challenging factors such
as trauma, iron salts, egg albumin, polymycin and glucocorti-
coids. Through his pioneering work, Seyle laid the foundation
for understanding this debilitating disease in humans, describing
it as a rare complication of CKD and secondary hyperparathy-
roidism involving the dermis and vasculature. Subsequently, our
Calcic uremic arteriolopathy
Pathophysiology, reactive oxygen species
and therapeutic approaches
Kurt M. Sowers1,2 and Melvin R. Hayden3-5,*
Universit y of Maryland; Divis ion of 1Nephrology; 2Physiology; Universit y of Missouri School o f Medicine; Depart ments of 3Internal Medi cine; 4Endocrinolog y Diabetes and
Metabol ism; 5Diabetes and Cardiov ascular Disease Resear ch Center; University of M issouri School of Med icine; Columbia, MI USA
Key words: calcific obliterative arteriolopathy, calciphylaxis, fetuin-A, inflammation, oxidative stress, sodium thiosulfate,
ultrastructure, vascular calcif ication
Abbreviations: CUA, calcific uremic arteriolopathy; CKD, chronic kidney disease; ESRD, end stage renal disease; VSMC,
vascular smooth muscle cell(s); ROS, reactive oxygen species; MGP, matrix GLA protein; AHSG, alpha2-heremans-schmid
glycoprotein; NFκB, nuclear factor kappaB; R ANKL, receptor activator of NFκB ligand; TNFα, tumor necrosis factor alpha;
IL-1, interleukin-1; IL-6, interleukin-6 ; ET-1, endothelin-1; eNOS, endothelial nitric oxide synthase; NO, nitric oxide; LDL-C,
low density lipoprotein-cholesterol; HDL-C, high density lipoprotein-cholesterol; NADPH, nicotinamide adenine dinucleotide
phosphate reduced; ADMA, asymmetrical dimethyl arginine; TNFα, tumor necrosis factor alpha; hsCRP, highly sensitive C
reactive protein; NKF KDOQI, national kidney foundation kidney disease outcomes quality initiative; HBO, hyperbaric oxygen;
iPTH, intact parathyroid hormone; PTX, parathyroidectomy; tPA, tissue plasminogen activator; STS, sodium thiosulfate; GSH,
glutathione; H2S, hydrogen sulfide; MMPs, matrix metalloproteinases; EMP, endothelial microparticles
contributes to the excess morbidity and mortality associated
with chronic kidney disease and end stage renal disease.
These same histopathologic conditions also occur in patients
without uremia and therefore, the term calcic obliterative
arteriolopathy could be utilized in these conditions.
Calcic uremic arteriolopathy (CUA)/calciphylaxis is an
important cause of morbidity and mortality in patients with
chronic kidney disease requiring renal replacement. Once
thought to be rare, it is being increasingly recognized and
reported on a global scale. The uremic milieu predisposes
to multiple metabolic toxicities including increased
levels of reactive oxygen species and inammation.
Increased oxidative stress and inammation promote
this arteriolopathy by adversely aecting endothelial
function resulting in a prothrombotic milieu and signicant
remodeling eects on vascular smooth muscle cells. These
arteriolar pathological eects include intimal hyperplasia,
inammation, endovascular brosis and vascular smooth
muscle cell apoptosis and dierentiation into bone forming
osteoblast-like cells resulting in medial calcication. Systemic
factors promoting this vascular condition include elevated
calcium, parathyroid hormone and hyperphosphatemia with
consequent increases in the calcium x phosphate product.
The uremic milieu contributes to a marked increased in
upstream reactive oxygen species—oxidative stress and
subsequent downstream increased inammation, in part,
via activation of the nuclear transcription factor NFκB and
associated downstream cytokine pathways. Consitutive
anti-calcication proteins such as Fetuin-A and matrix GLA
proteins and their signaling pathways may be decreased,
which further contributes to medial vascular calcication.
The resulting clinical entity is painful, debilitating and

110 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
arterioles and proximal regions, which are frequently associ-
ated with marked adiposity (Figs. 2B–D and 3). Once adipo-
subdermal fibrotic-thrombotic occlusion develops, the skin and
the underlying subdermal layers become necrotic and ulcerated,
subject to infection with an associated increase in morbidity and
mortality from systemic infection—sepsis. This model of media
calcified vasculature, intimal hyperplasia, endovascular fibrosis,
inflammation and associated procoagulant milieu predisposes
to fibrotic—thrombotic ischemia with ensuing necrosis (Figs. 1,
2B–D and 3).5-14
Recent evidence suggests that this clinical entity is multifac-
torial and increasingly common in patients of Caucasian eth-
nicity and female gender. Additionally, there has been noted
an association with the risk factors of hyperphosphatemia, high
alkaline phosphatase, low serum albumin and elevated calcium
x phosphate product even though normal or low calcium levels
may be present at the time of diagnosis in patients with CUA/
calciphylaxis.13
Histopathologic Diagnosis
Although CUA is a clinical diagnosis, histological confirma-
tion is suggested and remains the gold standard for definitive
diagnosis. Biopsies have described the pathognomonic lesions
of small arteries and arteriolar medial calcification (up to 600
micrometer) with intimal hyperplasia, inflammatory responses,
endovascular fibrosis, associated panniculitis, extravascular cal-
cium deposition, thrombosis and tissue necrosis (Figs. 1–3).5,6,9,12
This description has helped differentiate CUA from other similar
vasculopathies that may be present in a variety of patient popu-
lations presenting with isolated medial arteriolar calcification.
While medial vascular calcification itself may be an isolated find-
ing endemic to patients with renal insufficiency, diabetes melli-
tus, and atherosclerotic peripheral vascular disease not consistent
with CUA, intimal calcification is unique to the intimal athero-
sclerotic process.
Pathogenesis
CUA is associated with multiple histologic abnormalities that
collectively result in medial calcific, pro-stenotic—fibrotic,
proinflammatory and prothrombogenic arterioles compat-
ible with a calcific obliterative arteriolopathy—vasculopathy
(Fig. 2B –D).1,5-14 While vascular calcification was initially
described as a mere passive degenerative process, the present
understanding indicates that it is an active coordinated process
similar to bone modeling osteogenesis and physicochemical
deposition of mineral.4,5,13 ,16 The existing model for vascular cal-
cification begins with differentiation of vascular smooth muscle
cell(s) (VSMC) into chrondrocyte, osteoblast-like cellular phe-
notypes.16-18 This mechanism is initiated with the interaction of
uremia [hyperphosphatemia, multiple uremic toxins, and reac-
tive oxygen species (ROS)] and the decrease of local vascular cal-
cification inhibitory proteins such as Matrix Gla protein (MGP)
and the systemic globulin: fetuin-A—(α2-Heremans-Schmid
glycoprotein) AHSG (Fig. 4).
improved understanding of this complex clinical condition indi-
cates that the calcific changes in the vascular and dermal layers
of the skin involve a myriad of signaling and structural abnor-
malities. Indeed, these abnormalities include intimal hyperplasia,
inflammation, obliterative endovascular fibrosis, arteriolar medial
calcification, thrombotic cutaneous ischemia with necrotic der-
mal, subdermal and adipose tissue necrosis with skin ulceration,
and an undeniable increase in morbidity and mortality (Figs. 1
and 2).
CUA/calciphylaxis has been increasingly reported in the
literature over the past five years with new case reports or dis-
cussions published almost monthly.6 This may be attributed, in
part, to the increasing prevalence of CKD and its association
with the epidemic of obesity and the aging population in west-
ernized societies.6 ,8 ,14 Increased clinical recognition of CUA may
also be related to a better understanding of the pathophysiology
and mode of presentation. In this context, it is important to note
that up to 80% of the patients with CUA/calciphylaxis have
a very short life span and frequently die because of infectious
complications.1,6-14
Clinical Presentation
The initial presenting complaint is often that of a dull deep der-
mal pain with periods of neuritic-type dysesthesia associated with
palpable subcutaneous masses or dermal plaques. The dermal
changes are associated with erythema, violaceous mottling and
livedo reticularis (Fig. 2A), which progress to blackened regions
of eschar formation and eventually non-healing ulcerations
(Fig. 3A and B). Skin lesions were initially felt to occur primarily
on the lower limbs (acral or distal); however, these lesions seem
to be increasingly reported to involve the more obese tissues of
the abdomen, trunk, genital and inner thigh regions (proximal).
The eschars are quite painful, with involvement of the subdermal
Table 1. Risk factors for the development of CUA/calciphylaxis
1. Female gender* (5,6 ,13,17,18, 64)
2. Diabetes mellitus* (5, 6,14,17,18, 29, 64)
3. Hyperphosphatemia and concomitant calcium times phosphorus
product* (5,6,13,18,51,64)
4. Chronic Kidney Disease (CKD)—End Stage Renal Disease (ESRD)
(5,6 ,13,14,17,18, 64)
5. Hemo and peritoneal dialysis duration(6,13,14,17 )
6. Secondary hyperparathyroidism—Increased parathyroid
hormone(5,6 ,13,14,17,18, 51,64 )
7. Caucasian ethnicity(5 ,6,14 ,17)
8. Obesity(5,6 ,13,14,18 ,51,6 4)
9. Hypoalbuminemia (malnutrition and weight loss)(5,6,13,18,51,64)
10. Protein C and/or S deficiency(5, 64)
11. Elevated alkaline phosphatase(13,18,64)
12. Warfarin anticoagulation—inhibits vitamin K interfering with
matrix GLA protein(5,18,64)
13. Use of calcium phosphate binders(5,18,64)
Asterisks indicate strongest factors identified in multivariate analysis.13

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 111
adipocyte biology. Obesity is responsible for elevations in the det-
rimental cytokines—adipocytokines tumor necrosis factor alpha
(TNFα), interleukin-1 (IL-1) and interleukin-6 (IL-6) produc-
tion. Obesity and the obesity epidemic may be the driving force
behind the development of the cardiometabolic syndrome (insu-
lin resistance), type 2 diabetes mellitus, cardiovascular disease,
CKD, and increased oxidative stress—ROS.24 ,25 Obese subjects
have higher fasting levels of oxidative stress biomarkers compared
to non-obese subjects. Recently, it has been determined that
obese females experienced significantly increased oxidative stress
biomarkers (xanthine oxidase, malondialdehyde), ROS (H2O2),
triglycerides, glucose and significantly lower antioxidant capac-
ity in response to high fat meals that were sustained for longer
time periods as compared to non-obese subjects.25 This increase
in ROS could certainly be one of the mechanisms activating the
upstream NFκB and subsequent downstream adipocytokines—
cytokines allowing further insight for potential mechanisms
related to obesity-mediated morbidity.
Bone morphogenic proteins belong to the transforming
growth factor superfamily and are actively involved in induc-
ing de novo bone formation/osteoclast differentiation and
extraosseous calcification.16- 19 Of note, this action is dependent
on increased production of ROS, which are known activators of
nuclear factor kappa B (NFκB).20 MGP, a vitamin K dependent
localized protein, has been shown to inhibit bone morphogenic
protein-2. Fetuin-A is a hepatic synthesized systemic inhibitor
of hydroxyapatite formation (vascular calcification) and has
been noted to be reduced in states of renal failure, inflamma-
tion, and in patients with CUA/calciphylaxis (Fig. 4).21,22
Chronic inflammatory states, including alcoholic steatohepa-
titis, insulin resistance and CKD/ESRD are associated with
increased generation of NFκB and receptor activator of NFκB
ligand (RANKL) suggesting that the NFκB —osteoprotegerin/
RANK/RANKL axis is an important system in bone homeosta-
sis and vascular calcification (Fig. 4).23 In this regard, the afore-
mentioned disease states are associated with obesity and altered
Figure 1. Arteriolar remodeling and vascular calcication in calcic uremic arteriolopathy (CUA)/calciphylaxis. Arteriole model depicted is derived
from the pull out model of a normal small artery (upper right insert—boxed in area). This model demonstrates the four most common arteriolar nd-
ings observed in histologic sections in CUA/calciphylaxis: Vascular calcication, endovascular brosis, intimal hyperplasia, and inammatory response.
Intimal hyperplasia consists of the cellular expansion of the intima including endothelial hyperplasia (green). Excessive reactive oxygen species (ROS)
due to uremic toxins may be the driving force promoting this calcic obliterative arteriolopathy due to either endovascular brosis or thrombosis.
Ca, calcium; EEL, external elastic lamina; eNOS, endothelial derived nitric oxide synthase; IEL, internal elastic lamina; MΦ, macrophage; PO4, phosphate;
VSMC, vascular smooth muscle cell.

112 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
Unfortunately, attempted management of hyperphosphatemia
with calcium based phosphate binder’s upregulates gene tran-
scription of the cotransporter Pit-1.27 Increased expression of the
bone matrix protein osteopontin (an inducible inhibitor of vascu-
lar calcification), by immunostaining, has been identified in the
VSMC of the calcified vasculature in human patients with CUA
lesions and may predispose to sloughing of vascular cells into the
vessel lumen contributing to arteriole obliteration even prior to
arteriole thrombosis (Figs. 1 and 4).11,18, 28
As previously noted, vascular calcification may precede the
development of the skin changes and ulcerations associated with
CUA/calciphylaxis. This important concept has resulted in the
two stage concept set forth by Wilmer and Magro.29 Stage one is
the development of the actual vascular lesion (period of sensitiza-
tion induced by parathyroid hormone, vitamin D or high cal-
cium and phosphorus) (Figs. 1 and 2). Stage two comprises the
development of end-organ ischemia secondary to the expanding
Importantly, the vasoconstrictor and vascular growth pro-
moting substance endothelin-1 (ET-1) appears to be upregulated
through the facilitation of the NFκB pathway in CUA, promot-
ing VSMC calcification, vasoconstriction and loss of lumen
diameter.26 TNFα and other cytokines elicit a hypercoagulable
state through endothelial dysfunction with resultant release of
tissue factor, reduced endothelial cell protein C and S receptor
expression, decreased thrombomodulin expression, and ablation
of natural vascular heparin-like molecules.
Following the reduction in the above described inhibitory
molecules (MGP—fetuin-A) and accelerated ROS production,
VSMC are more susceptible to morphologic differentiation and
bone formation. Hyperphosphatemia is thought to be the trig-
gering factor for the transition from the constitutive VSMC to
osteoblast gene expression (osteogenic switch). The sodium/
phosphorus cotansporter (Pit-1) is the key protein involved in
hydroxyapatite deposition and vascular calcification (Fig. 4).
Figure 2. Early skin changes and histologic ndings in calcic uremic arteriolopathy/calciphylaxis. (A) depicts the dermal changes of livedo reticularis
(left anterior leg) prior to the initiation of hemodialysis. This image along with painful-palpable subcutaneous masses and plaques represent early skin
changes associated with CUA/calciphylaxis. (B) is an inverted colorized hematoxylin and eosin (H&E) stained image, which demonstrates medial calci-
cation (arrows) in an arteriole and adjacent venule. This image is from biopsy of a breast mass one year prior to the development of CUA/calciphylaxis
depicted in Figure 3. (C) portrays an outer adventitial location of vascular calcication (arrows) with H&E staining. (D) depicts arteriolar remodeling
including intimal hyperplasia, endovascular brosis (asterisks) and vascular calcication (arrows) resulting in calcic obliterative arteriolopathy with
endothelial brosis and arteriolar obliteration. H & E stain.

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 113
endothelial dysfunction with endothelial nitric oxide synthase
(eNOS) enzyme uncoupling resulting in decreased bioavail-
able endothelial derived nitric oxide (NO) (Figs. 4 and 5).17,3 0 - 33
Decreased bioavailable endothelial derived NO has a devastating
effect on the small arteries and arterioles resulting in a proinflam-
matory, proconstrictive and prothrombotic vasculature, which
may contribute significantly to the development of CUA/calci-
phylaxis and end-organ skin ulceration (Figs. 4 and 5).
Hyperglycemia, hyperhomocysteinemia, elevated β-2 micro-
globulin in uremia, elevated oxidized low density lipoprotein-
cholesterol (LDL-C), and low levels of antioxidant high density
lipoprotein-cholesterol (HDL-C) in atherogenic dyslipidemia are
additional factors that may increase ROS and contribute to vascu-
lar calcification.31-33 In addition to endothelial NOS uncoupling
(Fig. 5), there are other mechanisms that contribute to reduced
bioavailable NO. For example, non-phagocytic nicotinamide
adenine dinucleotide phosphate reduced (NADPH) oxidase
enzyme due to activation by increased local levels of angiotensin
II and aldosterone via their respective angiotensin type 1 and
mineralocorticoid receptors result in increased ROS production.
calcific vascular lesions now associated with obliterative endo-
vascular fibrosis and/or vascular thrombosis (period of challenge
such as trauma, surgery or any provoking inflammatory cytokine
surge). These stages may be concurrent or be separated by months
or years (Figs. 2 and 3).6,14,17,29
Reactive Oxygen Species (ROS)
in Pathogenesis of CUA/Calciphylaxis
ROS are known to be important signaling molecules in health.
However, excessive ROS are damaging to proteins, lipids, car-
bohydrates and nucleic acids, which prompt a classic “response
to injury” mechanism including inflammation (both acute and
chronic) supporting a cytokine surge, granulation and fibro-
sis.30-33 Figure 4 emphasizes the potential importance of ROS in
the development of vascular calcification in CUA and demon-
strates the salient relationship of the endothelium and VSMC in
this pathological process. ROS are excessive, robustly produced
in uremia, associated with multiple uremic toxins and the viscous
cycle of the inflammatory cytokine surge, VSMC apoptosis, and
Figure 3. Intravenous sodium thiosulfate (STS) induced wound healing. Images of CUA eschar (A), clean granulating bed following two weeks of
STS (B), healing phase (C) advancing to complete healing 3 months later in a 58 year old female treated with STS (D). Note the proximity of the skin
ulceration to the patient’s ileostomy and although this ulcer was small, it was highly vulnerable to infection and subsequent sepsis due to proximity
to ileostomy. The large subcutaneous palpable nodule (C) was outlined demonstrating its relation to the skin ulceration (∼7 x 14 cm) and gradually
regressed af ter 4 months of STS treatment.

114 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
Systemic events, such as surgical stress, promote ROS gen-
eration, which activate the nuclear transcription factor NFκB
via its receptor R ANK and activate the innate wound healing
mechanism. The NFκB—ANK/RANKL axis activation, in
turn, activates multiple downstream cytokines such as tumor
necrosis factor alpha (TNFα), interleukin (IL-1 and IL-6),
which may create a viscous cycle resulting in “inflammatory
cytokine surges” (Fig. 4) and may promote the development of
CUA/calciphylaxis. These inflammatory cytokine surges and
markers such as highly sensitive C reactive protein (hsCRP)
Xanthine oxidase, lipooxygenases and cyclooxygenases are capa-
ble of generating ROS via both NADPH oxidase dependent and
independent pathways,32,33 while asymmetrical dimethyl arginine
(ADMA) will complete for L-arginine and result in decreased
endothelial NO availability independent of eNOS uncoupling.
Due to the chronicity of these conditions, the natural occurring
antioxidants: catalase, superoxide dismutase and glutathione may
become depleted and add to the overall redox stress. Thus, exces-
sive production of ROS may play an important and integral role
in the development of CUA/calciphylaxis.
Figure 4. Potential mechanisms involving uremic toxins and reactive ox ygen species (ROS) in vascular calcication. Uremic toxins: Increased parathy-
roid hormone (PTH), phosphorus (Pi) and phosphate (PO4
-3), calcium, calcium x phosphorus product, vitamin D3, and ROS signicantly contribute to
vascular smooth muscle cell (VSMC) and/or pericyte (Pc) dierentiation into an osteoblast-like phenotype. Phosphate absorption into these cells is fa-
cilitated by the sodium phosphate cotransporter (Pit-1) resulting in an osteogenic switch due to activation of transcription factors: osteoblast-specic
cis-acting element (Osf2)—core binding factor alpha1 (Cbfa-1/Runx2). Osteocalcin, osteonec tin, bone morphogenic protein-2alpha and alkaline phos-
phatase (ALP) are inducers of calcication. In contrast, the systemic and local inhibitors of calcication fetuin-A—alpha2-Heremans-Schmid glycopro-
tein (AHSG) and matrix Gla protein (MGP) are decreased in uremia and calciphylaxis. Further, ROS and inammatory cy tokine surges may contribute
to decreased hepatic synthesis of fetuin-A (insert a). Uremic toxins—ROS promote uncoupling of endothelial nitric oxide synthase (eNOS) enzyme via
the oxidation of the requisite tetrahydrobiopterin (BH4) cofactor and results in the endothelium becoming a net producer of superoxide—ROS (insert
b). Additionally, decreased bioavailable eNO due to eNOS enzyme uncoupling promotes a proinammatory, proconstrictive, prothrombotic vascular
endothelium. ROS are also capable of promoting VSMC apoptosis in the arterial vascular wall (AVW) and when this occurs the matrix vesicles and
apoptotic bodies serve as nucleating sites for further calcium deposition in the extracellular matrix of the arteriole media (inserts b–e) (Fig. 1).

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 115
metabolic parameters as close to normal as possible utilizing
available dialysis techniques and medications. The following
seven therapeutic approaches are introduced randomly.
Calcium and phosphorus strategy. Initially all oral calcium
phosphate binders should be replaced with non-calcium phos-
phate binders (sevelamer, lanthanum carbonate, magnesium car-
bonate) and all oral calcium supplements should be discontinued.
The clinician may also attempt to lower the calcium concentra-
tion in the dialysate bath sequentially to 1.0–1.5 mEq/L as toler-
ated, while carefully monitoring serum calcium levels. Instead of
the standard three days/week dialysis regime, consider increas-
ing dialysis sessions from four to six treatment sessions per week
in order to lower the metabolic abnormalities associated with
ESRD.6,14,17,34
Improvement of hypoxia approach. The beneficial role of
hyperbaric oxygen (HBO) therapy has been reported in reviews
and multiple trials.1,18,3 4,35 Most of these reports utilize the
and elevated sedimentation rates in CKD and ESRD patients
on dialysis may decrease both local and systemic calcification
inhibitors such as matrix GL A protein (MGP) and fetuin-A
respectively. Elevated levels of ROS seem to be playing an
important role at each turn of events in vascular calcification
in addition to inflammation (Fig. 4). Importantly, ROS are
upstream of inflammatory events and play an important role
via the activation of NFκB and its receptor in the subsequent
downstream activation of inflammatory mediators as well as
vascular calcification.
Therapeutic Approaches to Prevent
and Treat CUA/Calciphylaxis
Importantly, the clinician should attempt to reach designated
national kidney foundation kidney disease outcomes quality ini-
tiative (NFK KDOQI) guidelines in order to bring all abnormal
Figure 5. Uncoupling of the eNOS enzyme results in the endothelium becoming a net producer of superoxide. This cartoon depicts many of the sig-
nicant metabolic events leading to endothelial nitric oxide synthase (eNOS) enz yme uncoupling in the endothelium. Reactive oxygen species (ROS)
and their oxidative eects of the requisite cofactor tetrahydrobiopterin (BH4) result in eNOS uncoupling. Excessive oxidation of BH4 resulting in the
generation of BH3 and BH2 will not run the eNOS reaction to completion. Instead the reaction uncouples and shifts to the C terminal reductase domain
and oxygen reacts with the nicotine adenine dinucleotide phosphorus reduced (NADPH) oxidase enz yme resulting in the generation of superoxide
[O2
-]. These dynamic metabolic sequences, involving the uncoupling of the eNOS, reaction result in a proinammatory, proconstrictive and prothrom-
botic endothelium, which contributes to endothelial dysfunction. Adapted and expanded with permission.17

116 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
STS has two unpaired electrons (one at the exposed singly
bonded oxygen and the other occurring at the exposed singly
bonded sulfur moiety of the disulfide bond), which it readily
donates to scavenge the unpaired electrons associated with ROS
(Fig. 6).17 The quenching of ROS associated with the increased
oxidative stress may allow recoupling of the uncoupled eNOS
enzyme and this effect may well contribute to the rather rapid
relief of the subdermal ischemia and the horrific pain associated
with CUA/calciphylaxis.6,14 ,17 Additionally, as STS reacts with
superoxide and unpaired electrons it may generate the potent nat-
urally occurring antioxidant glutathione (GSH).17 Recently, oral
STS has been shown to increase depleted hydrogen sulfide (H2S)
in an AV fistula mouse model of congestive heart failure sug-
gesting that STS is capable of reacting via various thiol reactions
and transsulfuration enzymes reacting with the endogenous sub-
strate, L-cysteine to generate H2S (Fig. 6).65 Some of the positive
effects produced by recoupling the uncoupled eNOS enzyme and
restoring bioactive endothelial derived NO include the following:
promotion of vasodilation of VSMC and counteracting VSMC
proliferation, decreasing platelet adhesiveness and monocytic
white blood cells reestablishing the teflon effect of the restored
endothelium, promotion of the endothelium’s anti-inflammatory,
antioxidant, antithrombotic, antiatherosclerotic and anti-fibrotic
function via quieting the activity of redox sensitive matrix metal-
loproteinases (MMPs).17
While the antioxidant effects of STS occur early in the
treatment of CUA, the chelating effects take longer; how-
ever, over time the chelation effects result in disappearance
of subcutaneous and vascular calcification and healing ensues
(Figs. 3 and 7).6,17,46,61,63,64,66 Improved endothelial dysfunction
and increased bioavailable NO via recoupling of the uncoupled
eNOS enzyme is currently thought to be playing an important
role in the rapid improvement of pain associated with CUA/
calciphylaxis.6 ,14,17 The positive effects of increased bioavail-
able NO may help to reverse the activation of the endothelium
with multiple vesicles and microparticle formation, endothelial
denudation and ultrastructure capillary—arteriolar vasocon-
striction (Fig. 8).
Side effects of intravenous STS consist of nausea, abdominal
cramping, vomiting and/or diarrhea if infused too rapidly (less
than one hour). Bone density should be monitored if STS is used
long term, since STS was demonstrated to decrease bone strength
in the recent rat model preventing vascular calcification.63
Most studies support the use of intravenous STS at a dosage
of 25 grams (two 12.5 gram vials diluted in 100 cc of normal
saline) during the last hour of hemodialysis and some suggest
that 12.5 grams per 100 cc of normal saline be used initially over
a one hour infusion as a test dose and if tolerated proceed to 25
grams.6,14,48-62,64 Additionally, STS has been used with peritoneal
dialysis52 and in pediatric patients (25 g/1.7 m2).54 The duration
of therapy depends on each individual patient; however, current
thoughts are that intravenous STS should be used for at least
two months beyond complete healing of the skin ulcerations.6,14,17
The relief from pain is usually rapid (days to weeks), while heal-
ing of skin ulcerations usually require several weeks to months of
treatment with longer treatment dependent on original size and
standard of care for reducing the known risk factors involved
with the addition of HBO therapy. Mechanisms include coun-
teracting local tissue hypoxia while improving wound healing
via increased angiogenesis and fibroblast proliferation with col-
lagen formation to promote wound healing. Additionally, HBO
therapy may increase bactericidal activity in infected wounds
by increasing the respiratory oxidative burst from neutrophillic
phagocytic NADPH oxidase.
Parathyroid hormone approach. Oral cinacalcet hydrogen
chloride to lower intact parathyroid hormone (iPTH) should be
considered initially while reserving parathyroidectomy (PTX) for
patients with markedly elevated iPTH levels or poor responders
to cinacalcet therapy.1,6,14 ,36
PTX with or without autotransplantation is a safe and effec-
tive surgical procedure for the treatment of resistant second-
ary hyperparathyroidism.37 Some retrospective studies and case
reports evaluating the use of PTX in patients resistant to medical
therapy have been positive,38 while others have not shown any
difference in survival rates with PTX,9 therefore, the role of PTX
remains controversial.39
Wound care approach. In patients with CUA/calciphylaxis
the importance of proper wound care and debridement was
recently reported to be associated with improved survival in a
retrospective study.9 Appropriate local wound care is recom-
mended with gentle wound debridement while avoiding deep or
wide surgical debridement and skin grafting. Appropriate sterile
dressings should provide a moist environment while removing
excessive exudates and be easy to apply and remove in order to
reduce surrounding skin trauma.1,6,9,14 ,17,28,40
Anti-inflammatory approach. Antiresorptive bisphospho-
nates are known to inhibit osteoclastic activity and possess
anti-inflammatory actions. These agents have the capability of
reducing local macrophage infiltration and activity including
decreased secretion of proinflammatory cytokines, thus facili-
tating the healing of CUA/calciphylaxis lesions.1,6 ,14,41,42 TNFα,
IL-6, and C-reactive protein are known positive regulators of
vascular calcification and may contribute to medial vascular and
tissue calcification in CUA. Therefore, the use of bisphospho-
nates such as intravenous pamidronate and ibandronate and oral
etidronate should be carefully considered in patients failing to
respond to other therapeutic modalities.43- 46
Antithrombotic approach. Low-dose tissue plasminogen acti-
vator (tPA) has been reported to be beneficial in a single case
report with predominately distal calciphylaxis.47 This type of
therapy seems logical since many cases of CUA are found to have
concurrent obliterative thrombus formation in addition to the
obliterative endovascular fibrosis in arterioles. However, further
studies are needed in order to properly evaluate this therapy.
Antioxidant approach. The potent antioxidant sodium thio-
sulfate (STS) has received considerable attention during the
past five years for the treatment of CUA/calciphylaxis.6,14 ,17,48-62
Importantly, intravenous STS has recently been shown to pre-
vent vascular calcification in a uremic rat model.63 Some leading
authors in this exciting field of study have even commented that
the most significant progress in the treatment of CUA/calciphy-
laxis has been the use of STS.64

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 117
is unknown with only 10 case reports identified to date (cen-
sus date 25 January 2010).54 ,67-70 Previous reviewers have noted
the following pertinent findings regarding the pediatric popula-
tion: Increased risk in males (90% of the cases reported to date)
with ESRD and secondary hyperparathyroidism, frequent distal
extremity and visceral organ involvement, worse prognosis with
acral-distal involvement, and increased resistance to medical
treatment compared to the affected adult population.69 However,
clinicians should keep in mind that with the continuing increase
in childhood obesity there may be a changing trend in the future
involving more proximal adipose tissue related skin ulceration.
There are now four successful outcomes regarding mortality
with intravenous STS.54,67 Recently, it has been suggested that
CUA/calciphylaxis requires early and aggressive intervention
with the use of multi-faceted therapeutic approaches as previ-
ously described with the recommendation of including conver-
sion from peritoneal dialysis to hemodialysis, intravenous STS
infusions, and hyperbaric oxygen therapy.67 Appropriate dose
adjustments should be made for the pediatric population71 and
intravenous STS at a dose of 25 g/1.7 m2 diluted in 100 cc of
number of ulcerations. In summary, one could say that the STS
story has evolved from Selye to Sulfates.
With each of the therapeutic approaches, it is wise to monitor
temperatures daily and aggressively obtain blood cultures should
there be any fever or chills suggesting sepsis, as these patients
have a weakened immune response and are extremely high-risk
for developing sepsis and endocarditis secondary to chronic skin
ulcerations.6,14,17 Also, it is appropriate to minimize each of the
positive regulators of vascular calcification. Special attention
should be given to the discontinuation of warfarin, as it has been
incriminated in the development of CUA/calciphylaxis due to
blocking vitamin K-dependent carboxylation of the matrix GLA
protein.17
CUA/Calciphylaxis in the Pediatric Population
The current literature regarding CUA/calciphylaxis and its man-
agement in the pediatric population is limited.67 Vascular and
soft tissue calcification is common in children occurring in up
to 60% in those with ESRD; however, the incidence of CUA
Figure 6. Potential mechanisms of sodium thiosulfate allowing for its antioxidant, vasodilator and chelation properties. This cartoon demonstrates the
molecular structure of sodium thiosulfate (STS) and its two readily donated unpaired electrons, which facilitate quenching of unpaired electrons, gen-
eration of the antioxidant glutathione (GSH), vasodilator hydrogen sulde (H2S), and calcium chelation forming the highly soluble calcium thiosulfate.
Adapted with permission.17

118 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
factor(s) precipitating CUA remain elusive at this point in time.
Similarly, the observation that a large number of patients can
share a similar constellation of risk factors and not develop CUA
remains unclear. In this review we have suggested that the reduc-
tion of inhibitors of calcification, especially fetuin-A, as a result
of a vicious ROS—inflammatory cytokine surge may be play-
ing an important role for this rapid deposition of calcium with
remodeling arteriolar obliterative and/or thrombotic occlusion.
Indeed, the liver plays an important role in protein synthesis and
it is known that a ROS-cytokine-inflammation axis is capable
of inducing the synthesis of innate acute phase reactant proteins
such as fibrinogen, serum amyloid A, and C reactive protein.
Concurrently, the ROS-cytokine-inflammation axis is capable
of inhibiting the hepatic synthesis of protective antioxidant pro-
teins such as albumin resulting in hypoalbuminemia (a known
risk factor for the development of CUA/calciphylaxis, Table 1)
and the systemic constitutive inhibitor of vascular calcification,
normal saline infused over one hour after each hemodialysis ses-
sion three times per week has been recommended (see section on
therapeutic approaches).6,54
Conclusion
CKD, ESRD, uremic toxins and dialysis (Fig. 4) result in a met-
abolic milieu creating the “perfect storm” for the development
of accelerated medial vascular calcification and remain a major
underlying predisposing factor for the development of CUA/
calciphylaxis.6,14 ,17,64,72
Physiological serum concentrations of calcium and phosphate
are several orders of magnitude above their solubility product,
which suggests that systemic (fetuin-A) and/or local (MGP)
mechanisms are operative in order to prevent extraosseous and
medial vascular calcification. While Wilmer and Magro’s two
stage theory helps to understand this situation,29 the exacting
Figure 7. No vascular calcication following four years of intermittent (3 times/week) intravenous sodium thiosulfate. These histopathologic gures
depict numerous open arterioles (arrows) (A–C) with no evidence of calcic obliterative arteriolopathy in the subdermal interstitium from biopsy of
skin adjacent to previously healed ulceration in Figure 3. In (D), note the specic stain for calcium (alizarin red) is negative. Insert (d) demonstrates
normal periarteriolar adventitial collagen (arrows), while inser t (d’) depic ts the positive control for alizarin red. Concurrently, this same patient as in
Figures 2 and 3 did not have any subcutaneous calcications when evaluated with bone scan (gure not shown).

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 119
thiosulfate may be of great value and serve as future biomarkers
for the early identification of CUA/calciphylaxis.
Biomarkers, in addition to oxidant stress and inflammation
that may be considered in the future, may relate to an activated,
dysfunctional or damaged—apoptotic endothelium and libera-
tion of endothelial microparticles (EMP) in CUA/calciphylaxis
(Fig. 8). EMP and multiple activated endothelial biomarkers
have been described including E-selectin, intercellular adhe-
sion molecule 1 (I-CAM-1), vascular cell adhesion molecule 1
(V-CAM-1), and von Willebrand factor (vWF).75 Interestingly, a
recent report has demonstrated that hypoxia is capable of induc-
ing both V-CAM-1 and a novel biomarker (S100A12), a calcium
fetuin-A (a negative acute phase protein).73,74 While this concept
is not proven and currently remains speculative, it may help to
provide a better understanding how the puzzling—post surgi-
cal patients (including those who are post renal transplant and
post parathyroidectomy) develop this devastating clinical con-
dition. This speculative concept may also help to explain why
some and not others with similar risk factor profiles and similar
laboratory values develop CUA/calciphylaxis and others do not.
Hopefully, the new fetuin-A knockout mouse model will aid in
a better understanding of the role of fetuin-A and its relation-
ship to CUA/calciphylaxis. Also, future experiments that mea-
sure fetuin-A in those patients treated with and without sodium
Figure 8. Microcirculation ultrastructure in calcic uremic arteriolopathy. (A) depicts a normal small arteriole (approximately 25–30 µm diameter) with
normal lining endothelial cell(s) (EC), and a single layer of supportive vascular smooth muscle cell(s) (VSMC), also note the open lumen with numer-
ous red blood cells (RBC), bar = 1 µm. (B) (in contrast) demonstrates a closed arteriolar lumen in a small arteriole (approximately 12–15 µm diameter)
from a patient’s subcutaneous skin ulceration with CUA compatible with endothelial dysfunction, vasoconstriction, and closed arteriolar lumen (CAL),
bar = 1 µm. (C) is a higher magnication of the boxed in region of the endothelium in (B) and may portray an activated endothelium demonstrating
multiple cy toplasmic projections containing numerous vesicles, bar = 0.2 µm. Additionally, note the free particles in the lumen, which may represent
endothelial microparticles (EMP) from the activated endothelium. Insert (c) displays an arteriole with endothelial denudation (arrows) and abnormal
ballooning of ECs with vacuole formation from same patient, bar = 2 µm. (D) depicts an open capillary lumen (CL) in the subcutaneous tissue of skin
biopsy adjacent to previous skin ulceration due to CUA (four years earlier, Fig. 3) treated with sodium thiosulfate (STS) for 4 years. Also note the normal
appearing pericytes (Pc) and multiple pericyte processes (PcP), which are restored and known to be very sensitive to oxidative stress. Inser t (d) por-
trays a normal open arteriole suggesting that STS may promote both capillary and arteriolar vasodilation.

120 Oxidative Medicine and Cellular Longevity Volume 3 Issue 2
therapy and some have stated that it is unlikely that such tri-
als will be conducted.18 Therefore, CUA/calciphylaxis reg-
istries that record various therapeutic approaches would be
extremely useful to identify further risk factors, biomarkers,
and potential abnorma lities to gain a better insight into its
pathogenesis, early diagnosis, and treatment. Furthermore,
monitoring and creating evidence based guidelines for future
treatment modalities in contrast to empirically based regimes
based on case reports and reviews as recommended in a recent
publication by Schlieper et al. may be of considerable ben-
efit.78 Current web based registries have been established in
Germany, US and UK (Table 2 ). We strongly urge clini-
cians treating patients with CUA/calciphylaxis to enter their
patient’s data and submit specimens into these registries when
appropriate.
When patients present with risk factors for CUA/calci-
phylaxis (Table 1) complaining of dermal pain and have the
associated skin changes of livedo reticularis or painful subcu-
taneous nodules or plaques, we as clinicians should be highly
suspicious for the future development of skin ulcerations.
Since it is these very non-healing skin ulcerations that place
our patients at such high risk for sepsis and increased mortal-
ity, we should not wait for the development of skin ulcerations
in order to aggressively treat the underlying metabolic abnor-
malities that are known to be risk factors for the development
of CUA/calciphylaxis.
Acknowledgements
Authors wish to thank James R. Sowers, Director Cosmopolitan
International Diabetes and Cardiovascular Center of the
University of Missouri, School of Medicine; Columbia, Missouri
for providing editorial assistance. Funding support has been pro-
vided by National Kidney Foundation Nephrology Fellow Basic
Science Grant (K.M.S.).
binding protein belonging to the S100 family, may function
as biomarkers76,77 and could potentially contribute to the early
identification of CUA/calciphylaxis prior to skin ulceration and
possibly monitor therapy. Additionally, future refinement of
endothelial microparticles assays could provide new vistas both
for evaluating and monitoring therapeutic approaches in CUA/
calciphylaxis.
Each of the seven therapeutic approaches (except the wound
care approach) offers the potential to reduce metabolic abnormali-
ties associated with CKD and ESRD requiring renal replacement
therapy. While each approach is very important, it may be noted
that the antioxidant approach with STS is directly or indirectly
involved in five of the seven therapeutic approaches and may rep-
resent an emerging component of most therapeutic strategies to
treat CUA.6,14,17,30 ,48- 62 Not only is STS a potent antioxidant but
also an integral component of the hypoxia, anti-inflammatory
and antithrombotic approaches. Additionally, through its more
delayed calcium chelation properties, it may be involved with the
calcium and phosphorous approach.
Currently, there are no randomized prospective controlled
clinical trials available upon which we can base our plan of
Table 2. Calcific uremic arteriolopathy/calciphylaxis registries
Germany: Calciphylaxie Register, International Collaborative
Calciphylaxis Network
www.calciphylaxie-register.ukaachen.de/
www.calciphylaxie-register.klinikum-coburg.de/
www.calciphylaxie.de/
US: Calciphylaxis Registry, KU Medical Center, Universit y
of Kansas
www2.kumc.edu/calciphylaxisregistry/
UK: UK Calciphylaxis Registry, International Collab orative
Calciphylaxis Network
www.calciphylaxis.org.uk/
References
1. Coates T, Kirkland GS, Dymock RB, Murphy BF,
Brealey JK, Mathew TH, et al. Cutaneous necrosis
from calcific uremic arteriolopathy. Am J Kidney Dis
1998; 32:384-91.
2. Pollock B, Cunliffe W, Merchant W. Calciphylaxis in
the absence of renal failure. Clin Exp Dermatol 2000;
25:389.
3. Goyal S, Huhn K, Provost T. Calciphylaxis in a patient
without renal failure or elevated parathyroid hormone:
the possible aetiological role of chemotherapy. Br J
Dermatol 2000; 143:1087-90.
4. Nigwekar SU, Wolf M, Sterns RH, Hix JK. Calciphylaxis
from nonuremic causes: a systematic review. Clin J Am
Soc Nephrol 2008; 3:1139-43.
5. Don BR, Chin AL. A strategy for the treatment of cal-
cific uremic arteriolopathy (calciphylaxis) employing a
combination of therapies. Clin Nephrol 2003; 59:463-
70.
6. Hayden MR, Goldsmith D, Sowers JR, Khanna R.
Calciphylaxis: calcific uremic arteriolopathy and the
emerging role of sodium thiosulfate. Int Urol Nephrol
2008; 40:443-51.
7. Angelis M, Wong LL, Myers SA, Wong LM.
Calciphylaxis in patients on hemodialysis: a prevalence
study. Surgery 1997; 122:1083-9.
8. Fine A, Zacharias J. Calciphylaxis is usually non-
ulcerating: risk factors, outcome and therapy. Kidney
Int 2002; 61:2210-7.
9. Weenig RH, Sewell LD, Davis MD, McCarthy JT,
Pittelkow MR. Calciphylaxis: natural history, risk fac-
tor analysis, and outcome. J Am Acad Dermatol 2007;
56:569-79.
10. Bleyer AJ, Choi M, Igwemezie B, de la Torre E, White
WL. A case control study of proximal calciphylaxis. Am
J Kidney Dis 1998; 32:376-83.
11. Ahmed S, O’Neill KD, Hood AF, Evan AP, Moe SM.
Calciphylaxis is associated with hyperphosphatemia and
increased osteopontin expression by vascular smooth
muscle cells. Am J Kidney Dis 2001; 37:1267-76.
12. Ketteler M, Biggar PH, Brandenburg VM, Schlieper G,
Westenfeld R, Floege J. Epidemiology, pathophysiol-
ogy, and therapy of calciphylaxis. Dtsch Arztebl 2007;
104:3481-5.
13. Mazhar AR, Johnson RJ, Gillen D, Stivelman JC,
Ryan MJ, Davis CL, et al. Risk factors and mortality
associated with calciphylaxis in end-stage renal disease:
Kidney Int 2001; 60:324-32.
14. Hayden MR. Calciphylaxis and the cardiometabolic
syndrome: the emerging role of sodium thiosulfate as
a novel treatment option. J Cardiometab Syndr 2008;
3:55-9.
15. Selye H. Calcihylaxis. Chicago, University of Chicago
Press 1962.
16. Moe SM, Chen NX. Mechanisms of vascular calcifica-
tion in chronic kidney disease. J Am Soc Nephrol 2008;
23:213-6.
17. Hayden MR, Tyagi SC, Kolb L, Sowers JR, Khanna
R. Vascular ossification-calcification in metabolic syn-
drome, type 2 diabetes mellitus, chronic kidney dis-
ease and calciphylaxis-calcific uremic arteriolopathy:
the emerging role of sodium thiosulfate. Cardiovasc
Diabetol 2005; 4:4.
18. Rogers NM, Teubner DJ, Coates PT. Calcific uremic
arteriolopathy: advances in pathogenesis and treatment.
Semin Dial 2007; 20:150-7.
19. Wozney JM, Rosen V, Celeste AJ, Mitsock LM,
Whitters MJ, Kriz RW. Novel regulators of bone for-
mation: molecular clones and activities. Science 1998;
242:1528-34.
20. Feng JQ, Xing L, Zhang JH, Xhao M, Horn D, Chan
J, et al. NFKappaB specifically activates BMP-2 gene
expression in growth plate chnondrocytes in vivo and
in a chondrocyte cell line in vitro. J Biol Chem 2003;
278:29130-5.
21. Schafer C, Heiss A, Schwarz A, Westenfeld R, Ketteler
M, Floege J, et al. The serum protein α2-Heremans-
Schmide glycoprotein/fetuin-A is a systemically acting
inhibitor of ectopic calcification. J Clin Invest 2003;
112:357-66.
22. Ketteler M, Bongartz P, Westenfeld R, Hildberger
JE, Mahnken AH, Bohm R, et al. Association of
low Fetuin-A (AHSG) concentrations in serum
with cardiovascular mortality in patients on dialysis;
a cross-sectional study. Lancet 2003; 361:827-33.

www.landesbioscience.com Oxidative Medicine and Cellular Longevity 121
60. Tindi A, Gauray K, Panda M. Non-healing painful
ulcers in a patient with chronic kidney disease and
role of sodium thiosulfate. A case report. Cases J 2008;
1:178.
61. Kyritsis I, Gombou A, Griveas I, Agroyannis I, Retsa K,
Agroyannis B. Combination of sodium, cinacalcet and
paricaicitol in the treatment of calciphylaxis with hyper-
parathyroidism. Int J Artif Organs 2008; 31:742-4.
62. Hackett BC, McAleer MA, Sheehan G, Powell FC,
O’Donnell BF. Calciphylaxis in a patient with normal
renal function: response to treatment with sodium
thiosulfate. Clin Exp Dermatol 2009; 34:39-42.
63. Pasch A, Schaffner T, Huynh-Do U, Frey BM, Frey FJ,
Farese S. Sodium thiosulfate prevents vascular calcifica-
tions in uremic rats. Kidney Int 2008; 74:1444-53.
64. Rogers NM, Coates PT. Calcific uraemic arteriolopa-
thy: an update. Curr Opin Nephrol Hypertens 2008;
17:639-40.
65. Sen U, Vacek TP, Hughes WM, Kumar M, Moshal KS,
Tyagi N, et al. Cardioprotective role of sodium thiosul-
fate on chronic heart failure by modulating endogenous
H2S generation. Pharmacology 2008; 82:201-13.
66. Yatzidis H. Successful sodium thiosulphate treatment
for recurrent calcium urolithiasis. Clin Nephrol 1985;
23:63-7.
67. Amin N, Gonzalez E, Lieber M, Salusky IB, Zaritsky
JJ. Successful treatment of calcific uremic arteriol-
opathy in a pediatric dialysis patient. Pediatr Nephrol
2010; 25:357-62.
68. Bakkalogu SA, Dursun I, Kaya A, Soylemezoglu O,
Hasanoglu E, Buyan N. Digital calciphylaxis progress-
ing to amputation in a child on continuous ambulatory
peritoneal dialysis. Ann Trop Paediatr 2007; 27:149-52.
69. Feng J, Gohara M, Lazova R, Antaya RJ. Fatal child-
hood calciphylaxis in a 10-year-old and literature
review. Pediatr Dermatol 2006; 23:266-72.
70. Imam AA, Mattoo TK, Kapur G, Bloom DA, Valentini
RP. Calciphylaxis in pediatric end-stage renal disease.
Pediatr Nephrol 2005; 20:1776-80.
71. Sanchez CP. Secondary hyperparathyroidism in chil-
dren with chronic renal failure: pathogenesis and treat-
ment. Paediatr Drugs 2003; 5:763-76.
72. Towler DA. Vascular calcification in ESRD: Another
cloud appears in the perfect storm-but highlights a
silver lining? Kidney Int 2004; 66:2467-8.
73. Lebreton JP, Joisel F, Raoult JP, Lannuzel B, Rogez JP,
Humbert G. Serum concentration of human alpha
2HS glycoprotein during the inflammatory process:
evidence that alpha2 HS glycoprotein is a negative
acute-phase reactant. J Clin Invest 1979; 64:1118-29.
74. Westenfeld R, Schafer C, Smeets R, Brandenburg VM,
Floege J, Ketteler M, et al. Fetuin-A (AHSG) pre-
vents extraosseous calcification induced by uremia and
phosphate challenge in mice. Nephrol Dial Transplant
2007; 22:1537-46.
75. Horstman LL, Jy W, Jimenez JJ, Ahn YS. Endothelial
microparticles as markers of endothelial dysfunction.
Front Biosci 2004; 9:1118-35.
76. Maiese K. Marking the onset of oxidative stress:
Biomarkers and novel strategies. Oxid Med Cell Longev
2009; 2:1.
77. Vince RV, Chrismas B, Midgley AW, McNaughton LR,
Madden LA. Hypoxia mediated release of endothelial
microparticles and increased association of S100A12
with circulating neutrophils. Oxid Med Cell Longev
2009; 2:2-6.
78. Schlieper G, Brandenburg V, Ketteler M, Floege J.
Sodium thiosulfate in the treatment of calcific uremic
arteriolopathy. Nat Rev Nephrol 2009; 5:539-43.
42. Pennanen N, Lapinjoki S, Urtti A, Monkkonen J.
Effect of liposomal and free bisphosphonates on IL-1
beta, IL-6 and TNFalpha secretion from RAW 264 cells
in vitro. Pharm Res 1995; 12:916-22.
43. Phanish MK, Kallarackal G, Rayanan R, Lawson TM,
Baboolal K. Tumoral calcinosis associated with pyrexia
and systemic inflammatory response in a haemodi-
alysis patient: successful treatment using intravenous
pamidronate. Nephrol Dial Transplant 2000; 15:1691-
3.
44. Monney P, Nguyen QV, Perroud H, Descombes E.
Rapid improvement of calciphylaxis after intravenous
pamidronate therapy in a patient with chronic renal
failure. Nephrol Dial Transplant 2004; 19:2130-2.
45. Musso CG, Enz PA, Guelman R, Mombelli C,
Imperiali N, Plantalech L, et al. Non-ulcerating cal-
cific uremic arteriolopathy skin lesion treated success-
fully with intravenous ibandronate. Perit Dial Int 2006;
26:717-8.
46. Shiraishi N, Kitamura K, Miyoshi T, Adachi M, Kohda
Y, Nonoguchi H, et al. Successful treatment of a patient
with severe calcific uremic arteriolopathy (calciphy-
laxis) by etidronate sodium. Am J Kidney Dis 2006;
48:151-4.
47. Sewell LD, Weenig RH, Davis MDP, McEvoy MT,
Pittelkow MR. Low dose tissue plasminogen activator
for calciphylaxis. Arch Dermatol 2004; 140:1043-8.
48. Cicone JS, Petronis JB, Embert CD, Spector DA.
Successful management of calciphylaxis with intra-
venous sodium thiosulfate. Am J Kidney Dis 2004;
43:1104-8.
49. Guerra G, Shah RC, Ross EA. Rapid resolution of
calciphylaxis with intravenous sodium thiosulphate
and continuous venovenous haemofiltration using low
calcium replacement fluid: case report. Nephrol Dial
Transplant 2005; 20:1260-2.
50. Brucculeri M, Cheigh J, Bauer G, Serur D. Long-term
intravenous sodium thiosulfate in the treatment of a
patient with calciphylaxis. Semin Dial 2005; 18:431-
4.
51. Meissner M, Bauer R, Beier C, Betz C, Wolter M,
Kaufmann R, et al. Sodium thiosulphate as a promising
therapeutic option to treat calciphylaxis. Dermatology
2006; 212:373-6.
52. Mataic D, Bastani B. Intraperitoneal sodium thiosul-
phate for the treatment of calciphylaxis. Ren Fail 2006;
28:361-3.
53. Tokashiki K, Ishida A, Kouchi M, Ishihara S, Tomiyama
N, Kohagura K, et al. Successful management of critical
limb ischemia with intravenous sodium thiosulphate
in a chronic hemodialysis patient. Clin Nephrol 2006;
66:140-3.
54. Araya CE, Fennell RS, Neiberger RE, Dharnidharka
VR. Sodium thiosulfate treatment for calcific uremic
arteriolopathy in children and young adults. Clin J Am
Soc Nephrol 2006; 1:1161-6.
55. Baker BL, Fitzgibbons CA, Buescher LS. Calciphylaxis
responding to sodium thiosulfate therapy. Arch
Dermatol 2007; 143:269-70.
56. Ackermann F, Levy A, Daugas E, Schartz N, Riaux A,
Derancourt C, et al. Sodium thiosulfate as first-line
treatment for calciphylaxis. Arch Dermatol 2007;
143:1336-7.
57. Subramaniam K, Wallace H, Sinniah R, Saker B.
Complete resolution of recurrent calciphylaxis with
long-term intravenous sodium thiosulfate. Australas J
Dermatol 2008; 49:30-4.
58. Soni S, Leslie WD. Bone scan findings in metastatic
calcification from calciphylaxis. Clin Nucl Med 2008;
33:502-4.
59. Raymond CB, Wazny LD. Sodium thiosulfate, bispho-
nates and cinacalcet for treatment of calciphylaxis. Am
J Health Syst Pharm 2008; 65:1419-29.
23. Kiechi S, Werner P, Knoflach M, Furtner M, Willeit J,
Schett G. The osteoprotegerin/RANK/RANKL system:
a bone key to vascular disease. Expert Rev Cardiovasc
Ther 2006; 4:801-11.
24. Hayden MR, Stump CS, Sowers JR. Organ involve-
ment in the cardiometabolic syndrome. J Cardiometab
Syndr 2006; 1:16-24.
25. Bloomer RJ, Fisher-Wellman KH. Systemic oxidative
stress is increased to a greater degree in young obese
women following consumption of high fat meal. Oxid
Med Cell Longev 2009; 2:19-25.
26. Wu SY, Zhang BH, Pan CS, Jiang HF, Pang YZ, Tang
CS. Endothelin-1 is a potent regulator in vivo in vascu-
lar calcification and in vitro in calcification of vascular
smooth muscle cells. Peptides 2003; 24:1149-56.
27. Yang H, Curinga G, Giachelli CM. Elevated extracel-
lular calcium levels induce smooth muscle cell matrix
mineralization in vitro. Kidney Int 2004; 66:2293-9.
28. Griethe W, Schmitt R, Jurgensen JS, Bachmann S,
Eckardt KU, Schindler R. Bone morphogenic protein-4
expression in vascular lesions of calciphylaxis: Journal
Nephrol 2003; 16:728-32.
29. Wilmer WA, Magro CM. Calciphylaxis: emerging
concepts in prevention, diagnosis and treatment. Semin
Dial 2002; 15:172-86.
30. Hayden MR, Kolb LG, Khanna R. Calciphylaxis and
the cardiometabolic syndrome. J Cardiometab Syndr
2006; 1:76-9.
31. Hayden MR, Tyagi SC. Intimal redox stress: accelerated
atherosclerosis in metabolic syndrome and type 2 dia-
betes mellitus: Atheroscleroapathy. Cardiovasc Diabetol
2002; 1:3.
32. Hayden MR, Whaley-Connell A, Sowers JR. Renal
redox stress and remodeling in metabolic syndrome,
type 2 diabetes mellitus and diabetic nephropathy:
paying homage to the podocyte. Am J Nephrol 2005;
25:553-69.
33. Nistala R, Whaley-Connell A, Sowers JR. Redox
control of renal function and hypertension. Antioxid
Redox Signal 2008; 10:2047-89.
34. Basile C, Montanaro A, Masi M, Pati G, DeMaio P,
Gismondi A. Hyperbaric oxygen therapy for calcific
uremic arteriolopathy (calciphylaxis): a case series. J
Nephrol 2002; 15:676-80.
35. Arenas MD, Gil MT, Gutierrez MD, Malek T,
Moledous A, Salinas A, et al. Management of calcific
uremic arteriolopathy (calciphylaxis) with a combi-
nation of treatments, including hyperbaric oxygen
therapy. Clin Nephrol 2008; 70:261-4.
36. Velasco N, MacGregor M, Innes A, Mackay I. Successful
treatment of calciphylaxis with cinacalcet—an alterna-
tive to parathyroidectomy? Nephrol Dial Transplant
2006; 21:1999-2004.
37. Drakopoulos S, Koukoulaki M, Apostolou T, Pistolas
D, Balaska K, Gavrill S, et al. Total parathyroidectomy
without autotransplantation in dialysis patients and
renal transplant recipients, long-term foll-up evalua-
tion. Am J Surg 2009; 198:178-83.
38. Girotto JA, Harmon JW, Ratner LE, Nichol TL, Wong
L, Chen H. Parathyroidectomy promotes wound heal-
ing and prolongs survival in patients with calciphylaxis
from secondary hyperparathyroidism. Surgery 2001;
130:645-50.
39. Bazari H, Jaff MR, Mannstadt M, Yan S. Case 7-2007. A
59 year old woman with diabetic renal disease and non-
healing skin ulcers. N Engl J Med 2007; 356:1049-57.
40. Bradley M, Cullum N, Nelson EA, Petticrew M,
Sheldon T, Torgerson D. Systematic reviews of wound
care management: (2). Dressings and topical agents
used in the healing of chronic wounds. Health Technol
Assess 1999; 3:1-35.
41. Cecchini MG, Felix R, Fleisch H, Cooper PH. Effects
of bisphosphonates on proliferation and viability of
mouse bone marrow derived macrophages. J Bone
Miner Res 1987; 2:135-42.