Community-acquired hypernatremia in elderly and very elderly patients admitted to the hospital: Clinical characteristics and outcomes

Abstract

Background
The clinical features, outcome and cost burden of community-acquired hypernatremia (CAH) in elderly and very elderly patients are not well known. Our aim was to investigate the etiologies, reasons for admission, clinical courses, outcomes, complications, and cost assessments of the elderly patients with CAH.

Material/Methods
We conducted a retrospective study in our tertiary hospital. Elderly and very elderly patients evaluated in the emergency department (ED) from January 1, 2010 to December 31, 2010 (n=4960) were included. Totally, 102 patients older than 65 years and diagnosed with CAH were evaluated. The patients were divided into 2 main groups according to their age: elderly (65–74 years old) (group 1) (n=38), and very elderly (>74 years) (group 2) (n=64).

Results
Our overall observed prevalence of CAH was 2.0% (n=102, 102/4960). In particular, the prevalences of CAH in group 1 and group 2 were 1.0% (38/3651) and 4.8% (64/1309), respectively (p<0.001). Totally, 62 patients had been treated by renin-angiotensin system (RAS) blockers (ie, ACE-inhibitors). Alzheimer’s disease had been diagnosed in 46.1% of the subjects. The mean Katz scores at the time of admission were 2.4±1.9 and 1.1±1.0 in group 1 and 2, respectively (p<0.001). The mean cost was higher in group 2 than in group 1 (2407.13±734.54 USD, and 2141.12±1387.14 USD, respectively) (p<0.01). The need for intensive care was significantly greater in group 2 as compared to group 1.

Conclusions
The important determinants of “CAH” in elderly subjects are accompanying Alzheimer’s disease, oral intake impairment, and concomitant treatment with RAS blockers.

Full text

Community-acquired hypernatremia in elderly and
very elderly patients admitted to the hospital: Clinical
characteristics and outcomes
Kenan Turgutalp1E, Onur Özhan2D, Ebru Gök Oğuz1B, Arda Yilmaz3B,
Mehmet Horoz4B, İlter Helvacı5C, Ahmet Kiykim1A
1 Division of Nephrology, Department of Internal Medicine, School of Medicine, Mersin University, Mersin, Turkey
2 Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Mersin
University, Mersin, Turkey
3 Department of Neurology, School of Medicine, Mersin University, Mersin, Turkey
4 Division of Nephrology, Department of Internal Medicine, School of Medicine, Harran University, Sanliurfa, Turkey
5 Silifke School of Applied Technology and Management, Department of Business Information Management, Mersin
University, Mersin, Turkey
Source of support: Departmental sources
Summary
Background:
The clinical features, outcome and cost burden of community-acquired hypernatremia (CAH) in
elderly and very elderly patients are not well known. Our aim was to investigate the etiologies, rea-
sons for admission, clinical courses, outcomes, complications, and cost assessments of the elderly
patients with CAH.
Material/Methods:
We conducted a retrospective study in our tertiary hospital. Elderly and very elderly patients eval-
uated in the emergency department (ED) from January 1, 2010 to December 31, 2010 (n=4960)
were included. Totally, 102 patients older than 65 years and diagnosed with CAH were evaluat-
ed. The patients were divided into 2 main groups according to their age: elderly (65-74 years old)
(group 1) (n=38), and very elderly (>74 years) (group 2) (n=64).
Results:
Our overall observed prevalence of CAH was 2.0% (n=102, 102/4960). In particular, the preva-
lences of CAH in group 1 and group 2 were 1.0% (38/3651) and 4.8% (64/1309), respectively
(p<0.001). Totally, 62 patients had been treated by renin-angiotensin system (RAS) blockers (ie,
ACE-inhibitors). Alzheimer’s disease had been diagnosed in 46.1% of the subjects. The mean Katz
scores at the time of admission were 2.4±1.9 and 1.1±1.0 in group 1 and 2, respectively (p<0.001).
The mean cost was higher in group 2 than in group 1 (2407.13±734.54 USD, and 2141.12±1387.14
USD, respectively) (p<0.01). The need for intensive care was significantly greater in group 2 as
compared to group 1.
Conclusions:
The important determinants of “CAH” in elderly subjects are accompanying Alzheimer’s disease,
oral intake impairment, and concomitant treatment with RAS blockers.
key words: elderly•community-acquiredhypernatremia•morbidity•mortality•cost
Full-textPDF: http://www.medscimonit.com/fulltxt.php?ICID=883600
Word count: 3341
Tables: 3
Figures: —
References: 23
Author’s address: Kenan Turgutalp, Division of Nephrology, Department of Internal Medicine, School of Medicine, Mersin University,
33079 Mersin, Turkey, e-mail: k.turgutalp@hotmail.com
Authors’ Contribution:
A Study Design
B Data Collection
C Statistical Analysis
D Data Interpretation
E Manuscript Preparation
F Literature Search
G Funds Collection
Received: 2012.02.13
Accepted: 2012.07.03
Published: 2012.12.01
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© Med Sci Monit, 2012; 18(12): CR729-734
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Background
Thirst is the ultimate defense against development of
hypernatremia. Elderly people typically have decreased
thirst, thus resulting in reduced water intake. The abil-
ity to concentrate urine also diminishes with advancing
age. Numerous factors, including female sex, infections,
hypertonic infusions, tube feedings, osmotic diuretics,
laxatives, and mechanical ventilation, increase the sus-
ceptibility of elderly persons to hospital-acquired hyper-
natremia [1].
Hypernatremia is present in about 1% of hospitalized pa-
tients over 60 years of age [2–4]. On the other hand, the
mortality rate, which is above 40% for hypernatremia, makes
it a more important issue [5]. More than two fold of increase
in the mortality in elderly patients with hospital-acquired hy-
pernatremia has been detected as compared to non-elderly
subjects [6]. However, data about the costs, clinical results,
related factors and prevalence of community-acquired hy-
pernatremia (CAH) are incomplete.
In Turkey, 7.2% of the total population is composed
of people above 65 years of age (http://www.tuik.gov.tr/
PreHaberBultenleri.do?id=8428), and by 2050 this age group
is expected to increase by 730% (http://www.tuik.gov.tr/
PreHaberBultenleri.do?id=8428). In this sense, the problems
specific to elderly people, along with their management,
should be well defined. The aim of this study was to ex-
plore the clinical features, results and cost of CAH in el-
derly subjects.
Material and Methods
We conducted a retrospective study in our tertiary hospi-
tal. Elderly and very elderly patients evaluated in the emer-
gency department (ED) from January 1, 2010 to December
31, 2010 (n=4960) were recruited. Subjects with plasma Na
+
>145 mEq/L were accepted as hypernatremic. Serum Na+
level between 145–160 mEq/L was defined as mild hyper-
natremia, and serum Na+ level >160 mEq/L was defined as
severe hypernatremia. The study included 102 patients old-
er than 65, diagnosed with CAH. The records of each hy-
pernatremic patient were reviewed.
We recorded blood pressure, volume status, mental and
motor status, fluid prescription, and laboratory findings
daily. The therapy and management of each patient had
been determined by the patient’s primary physician. In
patients identified as hypernatremic, the onset, duration,
and resolution of hypernatremia were determined on the
basis of an upper limit of 145 mmol/L. Clinical character-
istics, outcomes, accompanying problems, complications
and cost assessments of each patient were obtained. The
medical records of all patients were evaluated by one re-
viewer (KT).
The mean life expectancy in Turkey is 74 years. The patients
were divided into 2 groups according to age. Group 1 was
composed of “elderly” people aged 65 to 74 (n=38), and
group 2 had “very elderly” subjects above age 74 (n=64).
The study subjects had not been admitted by another hos-
pital in the 2 weeks before admission at our center.
Demographic data
The volume and composition of intravenous fluids, nutri-
tion, and oral water intake during hospitalization were re-
corded. Daily urine volume, based on the intake and out-
put record, was recorded for each hypernatremic patient.
Neurologic examination had been performed in all subjects
on admission. Motor examination had been performed by
a neurologist via physical examination. Katz index, which
identifies the patient’s independency status in his/her dai-
ly activities, had been determined by a neurologist. In this
sense, doing some activities themselves (eg, showering,
dressing, fulfilling toilet needs, the ability of movement,
and feeding were assessed. Scores above 6 were identified
as “fully independent”, 4 to 6 as “independent”, 2 to 4 as
“mildly dependent” and below 2 as “fully dependent” [7].
Mental status of the subjects had been assessed by a neurol-
ogist using Folstein’s MMSE scoring system. MMSE score
above 23 was defined as normal, 19 to 23 as borderline, and
below 19 as impairment in the mental status [8].
Cranial nerves and cardiopulmonary functions were record-
ed in all subjects at the time of admission. Hypernatremia
etiologies, features related with treatment course (eg, type
of fluid used, and Na+ level correction time), drugs which
were discontinued, neurological findings and complications,
clinical outcome, causes of death, costs, and factors related
to these parameters were explored. The causal relation of
hypernatremia with morbidity and mortality was determined
during data analysis by the consensus of all investigators.
Laboratory tests
Values for serum sodium, potassium, chloride, total carbon
dioxide, glucose, blood urea nitrogen, creatinine, calcium,
and plasma osmolality were recorded daily by the patient’s
managing physician.
Serum Na
+
, plasma glucose, serum blood urea nitrogen
(BUN) and creatinine levels were measured using an
Olympus AU 640 Chemistry Immunoanalyzer (Tokyo,
Japan). Serum potassium, magnesium, chloride, calcium,
phosphate, serum albumin and TSH (thyroid stimulating
hormone) levels, as well as urine density and CRP levels,
were measured by use of a Cobas Integra 800 Chemistry
Analyzer (Basel, Switzerland). GFR (eGFR) was calculated
with the “Modification of Diet in Renal Disease” MDRD for-
mula, which can be shown as MDRD: eGFR = 170 × [Scr]
– 0.999 × [age] – 0.176 × (0.762 if the subject is female) ×
(1.180 if the patient is black) × [BUN] – 0.170]. BUN/cre-
atinine ratio was measured on admission for each subject.
Cerebral computerized tomography and magnetic reso-
nance imaging were performed if indicated.
Statistics
The Shapiro-Wilk test was used to test the numeric data
in terms of its convenience for normal distribution. While
parametric tests were used for the assessment of variables
showing normal distribution, non-parametric tests were
used if normal distribution was not detected. For the com-
parison of the 2 independent categoric groups in terms of
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numeric variables, either Student’s t test or Mann-Whitney
U tests were used according to the distribution of the data.
For the comparison of categoric variables where more than
2 independent groups were involved, one-way ANOVA test
was used. Tukey HSD test was used to determine the pair-
wise differences between the subgroups when the omnibus
test ANOVA showed significant statistical values. Pearson
chi-square test was applied according to the assumptions
gathered from the comparisons of 2 categoric variables.
For testing a possible linear association between 2 numer-
ic variables, Spearman-Rho test was used. We calculated
6-month mean medical costs, and used analysis of variance
(ANOVA) to test for group differences. Generalized linear
models were used to calculate unadjusted and adjusted ef-
fects of hypernatremia on 6-month costs. Type one error
was determined to be 0.05. SPSS 16 and MedCalc 11.5 sta-
tistics programs were used.
results
The mean age was 76.9±7.3 years (ranging from 65 to 97).
Descriptive statistics of both groups are shown in Table 1.
Total CO2 levels, urine volume on admission, and serum
osmolarity were not different in both groups (p>0.05).
Overall observed prevalence of CAH was 2.0% (n=102,
102/4960). The prevalence of CAH in group 1 was 1.0%
(38/3651) and group 2 was 4.8% (64/1309) (p<0.001).
Presentation reasons
The most common reasons of admission were oral intake
impairment 76.4% (n=78), nausea and vomiting 13.7%
(n=14), and diarrhea 9.8% (n=10). Oral intake impairment
as the reason of application was statistically significantly
higher as compared to other reasons (p<0.05). Between 2
groups, no difference was detected in terms of the admis-
sion reasons (p>0.005)
Co-morbidities
The most common co-morbidities for both groups are shown
in Table 2, with Alzheimer’s disease statistically significant-
ly higher than the others (p<0.05). When groups 1 and
2 were compared, results were similar (p>0.05), showing
80.4% (n=82) of the subjects were hypotensive, 3.9% (n=4)
were normotensive, and 15.7% (n=16) were hypertensive.
Features Group 1 (n=38) Group 2 (n=64) p
Age (Year) 69.83±3.3 81.25±5.5 <0.05
Gender (male/female) 21/17 39/25 NS
Serum Na+ level on admission (mmol/L) 158.22±7.0 157.17±7.6 NS
Fasting plasma glucose(mg/dL) 101.16±31.36 99.46±31.36 NS
Potassium (mEq/l) 4.38±0.58 4.67±0.76 NS
Urea (mg/dl) 132.08±31.39 134.12±23.61 NS
Creatinine (mg/dl) 0.56±0.20 0.65±0.02 NS
Serum albumin (gr/dl) 3.7±1.2 3.3±1.4 <0.05
GFR(ml/minute) 76.3±8.1 72.1±7.3 <0.05
Systolic blood pressure(mmHg) 101.20±11.21 102.34±13.8 NS
Diastolic blood pressure (mmHg) 68.15±5.92 66.81±4.76 NS
Serum osmolality (mosm/kg-H2O) 337.47±18.26 335.23±17.65 NS
Triglyceride (mg/dl) 127.89±60.72 131.23±43.87 NS
Total Cholesterol (mg/dl) 172.38±34.32 176.60±48.54 NS
Mechanical ventilator need (%) 25 75 <0.001
Intensive care need (%) 33 67 <0.001
Mean intensive care duration (days) 8.02±12 12.13±1.53 <0.001
Duration of hospitalization (days) 12.11±7.2 15.50±7.1 <0.05
Mortality (%) (n) 47.3 (18) 64.0 (41) <0.001
Katz score* 2.4±1.9 1.1±1.0 <0.001
MMSE score* 21.1±8.1 12.5±7.5 <0.001
Table 1. Comparative clinical and laboratory features of both groups.
NS – not signicant; * at the time of admission.
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Factors responsible for CAH
The common clinical factors responsible for CAH are
shown in Table 3. Totally, 62 patients were on RAS block-
er medications. Mean duration of RAS blocker treatment
in groups 1 patients was 91.0±25.2/d and in group 2 pa-
tients was 88.1±15.1/d before developing hypernatremia
(p>0.05). Interestingly, oral intake impairment along with
the consumption of RAS blockers (angiotensin-converting
enzyme inhibitors and/or angiotensin II receptor blockers)
seemed to be significantly higher as compared to other rea-
sons (p<0.05). When groups 1 and 2 were compared with
each other, the possible causes of CAH were found in simi-
lar ratios and no statistical difference was detected (p>0.05).
Scores
The Katz scores at the time of application in groups 1 and
2 were 2.4±1.9 and 1.1±1.0, respectively (p<0.001). Mean
MMSE score in group 1 was 21.1±8.1 and 12.5±7.5 in group
2 (p<0.001)
There was a negative correlation between scores (Katz and
MMSE scores) and duration of hospitalization (p<0.05; for
Katz and MMSE scores, r=–0.39 and -0.41, respectively) as
well as with costs (p<0.05, for Katz and MMSE scores r=–0.33
and –0.37, respectively.) On the other hand, no relationship
was detected between the scores and other parameters such
as intensive care and mechanic ventilation needs, compli-
cations and mortality rates.
General complications
In 36.3% (n=37) of subjects there were no complications.
The most common complications of the hypernatremic sub-
jects were community-acquired pneumonia (n=4), commu-
nity-acquired uncomplicated urinary tract infection (n=4),
nosocomial pneumonia (n=14), nosocomial urinary tract
infection (n=12), gastrointestinal hemorrhage (n=5), acute
coronary syndrome (n=5), hyponatremia (n=5), and stroke
(n=4). There was no significant statistical difference between
the groups in terms of the complication types and preva-
lence ratios (p>0.05). No sex difference was found for com-
plication type and prevalence.
Intensive care and/or mechanical ventilation need
There were significantly more subjects needing intensive
care (n=67) than subjects not needing intensive care (n=35)
(p<0.05). All of the subjects requiring intensive care needed
mechanical ventilation. Mortality was 75% (n=50) among
those needing intensive care and 25% (n=9) of the remain-
ing ones died (p<0.05). The ex ratio of the patients with
mechanical ventilator need was 83% (n=55) and 23% (n=8)
for the subjects not requiring intensive care. The healing ra-
tio of the subjects not showing mechanical ventilator need
was higher (p<0.001). When groups 1 and 2 were compared
with each other, intensive care and/or mechanical ventila-
tor needs and complication ratios were similar and there
was no statistical difference.
Treatment
Serum Na
+
level correction speed and relation with clinical
complications independent of age were evaluated and fol-
lowing results were gathered: In patients where Na+ levels
were normalized within 0 to 24, 24 to 48, 48 to 72 and more
than 72 hours, 55.2% (n=16), 47.7% (n=21), 33.3% (n=6),
and 45.5% (n=5) respectively, did not show any complica-
tions. However, encephalopathy ratios were 8.8%, 6.9%,
7.2%, and 45.5%, respectively, for the same correction du-
rations. However, number of patients was insufficient for
statistical analysis. In patients with normalization durations
of Na+ within 24 to 48 and 48 to 72 hours, fewer complica-
tions were observed. Similar ratios and results were gath-
ered in group 1 and 2 (p>0.05).
Length of hospital stay
While mean length of hospital stay of all patients cured from
hypernatremia was 10.8±4.9 days, mean length of hospital
stay of subjects who died either from hypernatremia or oth-
er reasons was found to be 15.1±10.2, which is statistically
significant (p<0.05).
When the serum Na
+
level at the time of admission was com-
pared with length of hospital stay, we found that as the Na+
level increased, the length of hospital stay increased as well,
but this was not statistically significant (r=0.177, p=0.102). In
addition, there was a negative correlation between the hos-
pital stay and the scores of both Katz and MMSE (r=–0.39,
p<0.05, and r=–0.41, p<0.05).
Clinical outcome and mortality
Mortality occurred in 30.5% (n=18) of group 1 and 69.5%
(n=41) of group 2, an overall of 57.8% (n=59) of the sub-
jects died (p<0.005). Mild hypernatremia (145–160 mEq/L)
was detected in 31 (81.5%) subjects in group 1 and 41
Co-morbidities n (%)
Alzheimer disease 47 (31.4)
Alzheimer disease + Hypertension 15 (14.7)
Diabetes mellitus + Hypertension 12 (11.8)
Cerebrovascular event 9 (8.8)
Heart failure 9 (8.8)
Table 2. The most seen accompanying disorders in patients with
hypernatremia.
Accompanying disease n (%)
Oral intake impairment+ ACE-inhibitor use 47 (31.4)
Oral intake impairment + ARB use 15 (14.7)
Vomiting 12 (11.8)
Table 3. Most common clinical causes of community-acquired
hypernatremia.
ACE – angiotensin converting enzyme; ARB – angiotensin II receptor
blocker.
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(64%) subjects in group 2 (p<0.05). Severe hypernatremia
was detected in 7 (18.5%) and 23 (36%) patients in group
1 and group 2, respectively (p<0.001). The mortality ratios
in group 1 for the patients with mild and severe hyperna-
tremia were 41.9% (n=13) and 71.4% (n=5), respective-
ly; whereas they were 56.1% (n=23) and 78.2% (n=18), re-
spectively, in group 2.
In group 1, 6 patients (6%) were hypernatremic at time
of death, compared to 21 patients (35.5%) in group 2
(p<0.001). There were some contributing factors to mortal-
ity, including: multiorgan failure syndrome in 11 patients,
ventilator-associated pneumonia in 11 patients, sudden car-
diac death in 4 patients, urosepsis and septic shock in 4 pa-
tients, non-sustained ventricular tachycardia in 3 patients,
sustained increases in ventricular rate in atrial fibrillation
in 2 patients, severe upper gastrointestinal hemorrhage in
2 patients, sustained delirium in 2 patients, and acute myo-
cardial infarction in 1 patient. Most of the deaths cannot
be directly attributed to the hypernatremia itself. Based on
careful review of the medical records, we believe that hy-
pernatremia partially contributed to mortality in only 19
patients (32.2%).
The mortality rates for the patients whose Na+ levels were
corrected within 0 to 24, 24 to 48, 48 to 72, and more than
72 hours were found to be 55.2%, 33.3%, 45.5%, and 47.7%,
respectively. The mortality rates were higher in patients
in which Na+ levels were normalized within 24 and more
than 72 hours, as compared to other treatment durations
(p<0.05), for both groups.
Forty-three patients recovered from CAH; 6 of them had
speech defect, and 2 had hemiparesis due to stroke.
Cost analysis
We used generalized linear models to calculate unadjust-
ed and adjusted effects of hypernatremia on 6-month costs.
The mean cost of a hypernatremic subject was 2251.6±1085.5
United States Dollars (USD). Mean costs for group 1 and
group 2 were 2141.1±1387.1 and 2407.1±734.5, respectively
(p<0.05). Although it seemed that there was a positive cor-
relation between the baseline levels of Na
+
and costs, it had
no statistical meaning (r=0.099, p=0.320). We found that hy-
pernatremia was an independent predictor for 6-month cost
regardless of age, sex, and co-morbid conditions.
discussion
Although there is abundant data on hospital-acquired hy-
pernatremia (in pediatric and adult subjects during their
hospital stay), the clinical characteristics, outcomes and
economic burdens of CAH are not well known [9]. On the
other hand, only a few studies are available regarding the
causes, accompanying clinical problems, need for intensive
care, duration of normalization of Na
+
level, costs and clin-
ical results of hypernatremia in elderly (>65y) and very el-
derly (>74y) subjects. With this retrospective demographic
study, we have shown that the most common cause of CAH
in patients above age 65 is dehydration due to reduced oral
intake and concomitant treatment with RAS blockers. We
found that the subjects very often developed respiratory
problems requiring ventilation, with high mortality rates.
The very elderly group needed more care and assistance
at the time of admission as compared to the elderly group.
The mental and motor status was worse and the mortality
rate was higher, as well. Alzheimer’s was the most common
accompanying disease for both groups.
Age-related declines in organ function and appetite, illness
and disability, and increased fluid requirements predispose
older adults to dehydration and hypertonicity. In a cohort
study, Thunhorst et al found that compared to young rats,
old rats drink less water in response to several thirst-induc-
ing stimuli [10]. In addition, they showed that the amount
of liquid taken in the old group was less than in the young
group. Both middle-aged and old rats were less able than
young rats to repair their water deficits after sodium load-
ing, attributable almost entirely to their reduced drinking
responses compared with young rats [10]. Another mecha-
nism that leads to hypernatremia is that although the anti-di-
uretic hormone level is increased, urine concentrating abili-
ty in the elderly is impaired [11]. On the other hand, Latcha
et al found that hypoangiotensinemia impairs the secretion
of arginine vasopressin, which increases the predisposition
to hypernatremia [12]. The seriousness of Alzheimer’s dis-
ease accompanying hypernatremia may be another factor
that hinders patients from drinking sufficiently and regu-
larly. Furthermore, antihypertensive agents that blockade
the RAS cause hypoangiotensinemia and therefore partic-
ipate in this process.
Kettritz et al. reported that the mortality rate is increased
approximately 7-fold in elderly hypernatremic subjects as
compared to young people [5]. Alshayeb et al showed that
when Na
+
level is increased to a value more than 160 mEq/L,
the mortality rate increases to 75% [13]; their study includ-
ed 131 elderly hypernatremic subjects with mean Na+ lev-
el of 159±3mEq/L and mean age of 82.2. Warren et al, in
a multicentric study, found 6-fold more hypernatremia in
patients aged 85 to 99, as compared to subjects ages 65 to
70 [14]. Our study revealed that hypernatremic patients
older than 75 had significantly higher mortality rates com-
pared to subjects ages 65 to 75. Daggett et al., in their ret-
rospective study in which patients with serum sodium level
>155 nmol/l were assessed as severe hypernatremic, report-
ed that mortality rates increase parallel to the increase in
serum Na+ levels [15]. In our study, on the other hand, for
both groups we found that the mortality rates were higher
in patients with severe hypernatremia as compared to pa-
tients with mild hypernatremia.
The factors determining the course of treatment are the ra-
pidity of development and the severity of hypernatremia,
along with being symptomatic or not. The target in acute
symptomatic hypernatremia is to reduce the serum Na+ lev-
el 1.0 mEq/L/hour. Horn et al. reported that normaliza-
tion of Na
+
level in hypernatremic subjects should be done
as soon as possible if any of complications have occurred
[16]. However, they suggested that in the opposite situation
this correction would be better if done slowly [16]. While
some authors indicate that patients recover best from en-
cephalopathy if normalization of Na+ level is done within
72 hours [17], others say that mental functions can be per-
manently impaired if normalization takes more than 96
hours [12,18]. Samuels et al., on the other hand, report-
ed that permanent mental impairment and death could
Med Sci Monit, 2012; 18(12): CR729-734 Turgutalp K et al – Community acquired hypernatremia in elderly and very elderly
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occur if the normalization is achieved before day 1 [19].
In this sense they have suggested that achieving normaliza-
tion within 3 to 4 days would decrease the mortality rates
to the minimum level. In our study, mental problems and
increased mortality rates were most commonly seen when
serum Na+ level normalized within the first 24 hours or af-
ter 72 hours. Our study’s results in terms of treatment du-
rations were similar to the results of some other studies re-
garding the normalization speed in hypernatremic subjects.
A variety of authors have reported possible risk factors for the
development of hypernatremia, such as being older than 65,
being female, having mental status impairment, infections,
and some medical treatments, especially in subjects needing
care [20]. In our study, hypernatremia was detected more
in men than women. Darmon et al. recruited 1245 patients,
detecting hypernatremia in 228 subjects, and finding bacte-
rial infections to be the most common cause of hypernatre-
mia in patients with mean age above 65 years [21]. In our
study the most common etiological factors for hypernatre-
mia were oral intake impairment and use of RAS blockers.
Angiotensin II is the direct stimulator of thirstiness [22].
Treatment with RAS blockers in elderly subjects increas-
es the deterioration of the sensation of thirstiness, which
is in fact already being damaged. Moreover, RAS blockers
decrease the reabsorption of water from the tubules [23].
Our study shows that the treatment of RAS blockers facili-
tates the development of hypernatremia in elderly people.
Warren et al. found in their multicentric study that hyper-
natremic elder subjects had a very heavy cost burden. They
stated that 6.7% of the 10 million hospitalized elderly sub-
jects were hospitalized due to hypernatremia caused by de-
hydration. In addition they found that each patient had
a mean cost of 2.942 USD/year, leading to a yearly total
cost of $446 million USD [14]. In our study, we found that
a patient who is hospitalized due to CAH incurs a mean
cost of $2251.2±1085.0 USD. Detailed examination reveals
that for the elderly and very elderly groups the costs were
2141.7±1387.2 and 2407.1±734.5 USD, respectively. This
seems to be clear evidence that the costs increase as the
ages of the subjects increase, and this might be associated
with the increase in the co-morbidities as the patients aged.
conclusions
The main features of elderly and very elderly patients with
CAH are that Alzheimer’s is the most common accompany-
ing disease. Moreover, they have impaired and inadequate
oral intake, are very often treated with RAS blockers, and
most are hypotensive at time of admission. Another im-
portant feature is that the very elderly subjects with CAH
have greater needs for intensive care and mechanical ven-
tilation. Clinically, an important question is how these re-
sults could aid in preventing and treating hypernatremia in
the elderly and very elderly. In our opinion, prevention of
hypernatremia requires close monitoring of daily hydration
with convenient salines, and careful prescription of medi-
cations such as RAS blockers.
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