Vitamin A Deficiency after Gastric Bypass Surgery: An Underreported Postoperative Complication

Abstract

Introduction. Few data are available on vitamin A deficiency in the gastric bypass population.
Methods. We performed a retrospective chart review of gastric bypass patients (n = 69, 74% female). The relationship between serum vitamin A concentration and markers of protein metabolism at 6-weeks and 1-year post-operative were assessed.
Results. The average weight loss at 6-weeks and 1-year following surgery was 20.1 ± 9.1 kg and 44.1 ± 17.1 kg, respectively. At 6 weeks and 1 year after surgery, 35% and 18% of patients were vitamin A deficient, (<325 mcg/L). Similarly, 34% and 19% had low pre-albumin levels (<18 mg/dL), at these time intervals. Vitamin A directly correlated with pre-albumin levels at 6 weeks (r = 0.67, P < 0.001) and 1-year (r = 0.67, P < 0.0001). There was no correlation between the roux limb length measurement and pre-albumin or vitamin A serum concentrations at these post-operative follow-ups. Vitamin A levels and markers of liver function testing were also unrelated.
Conclusion. Vitamin A deficiency is common after bariatric surgery and is associated with a low serum concentration of pre-albumin. This fat-soluble vitamin should be measured in patients who have undergone gastric bypass surgery and deficiency should be suspected in those with evidence of protein-calorie malnutrition.

Full text

Hindawi Publishing Corporation
Journal of Obesity
Volume 2011, Article ID 760695, 4pages
doi:10.1155/2011/760695
Clinical Study
Vitamin A Deficiency after Gastric Bypass Surgery:
An Underreported Postoperative Complication
Kerstyn C. Zalesin,1, 2 We n d y M . M i l l e r , 1Barry Franklin,1Dharani Mudugal,1
Avdesh Rao Buragadda,1Judith Boura,1Katherine Nori-Janosz,1David L. Chengelis,1
Kevin R. Krause,1and Peter A. McCullough1
1Divisions of Cardiology, Nutrition and Preventive Medicine, Department of Medicine, William Beaumont Hospital,
4949 Coolidge Highway, Royal Oak, MI 48073, USA
2Divisions of Nutrition, and Preventive Medicine, Department of Internal Medicine, William Beaumont Hospital,
4949 Coolidge Highway, Royal Oak, MI 48073, USA
Correspondence should be addressed to Kerstyn C. Zalesin, kzalesin@beaumont.edu
Received 10 June 2010; Accepted 27 August 2010
Academic Editor: Francesco Saverio Papadia
Copyright © 2011 Kerstyn C. Zalesin et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Introduction. Few data are available on vitamin A deficiency in the gastric bypass population. Methods.Weperformeda
retrospective chart review of gastric bypass patients (n=69, 74% female). The relationship between serum vitamin A
concentration and markers of protein metabolism at 6-weeks and 1-year post-operative were assessed. Results. The average weight
loss at 6-weeks and 1-year following surgery was 20.1±9.1kg and 44.1±17.1 kg, respectively. At 6 weeks and 1 year after
surgery, 35% and 18% of patients were vitamin A deficient, (<325mcg/L). Similarly, 34% and 19% had low pre-albumin levels
(<18 mg/dL), at these time intervals. Vitamin A directly correlated with pre-albumin levels at 6 weeks (r=0.67, P<0.001)
and 1-year (r=0.67, P<0.0001). There was no correlation between the roux limb length measurement and pre-albumin or
vitamin A serum concentrations at these post-operative follow-ups. Vitamin A levels and markers of liver function testing were also
unrelated. Conclusion. Vitamin A deficiency is common after bariatric surgery and is associated with a low serum concentration of
pre-albumin. This fat-soluble vitamin should be measured in patients who have undergone gastric bypass surgery and deficiency
should be suspected in those with evidence of protein-calorie malnutrition.
1. Introduction
Obesity, defined as a body mass index (BMI) ≥30 kg/m2,is
a chronic disease with major health and economic implica-
tions and is recognized as one of the greatest contributors
of excessive morbidity and mortality in the 21st century.
Approximately 30% of the American population is obese,
making it the leading nutritional disorder in our society
[1]. This trend has escalated to epidemic proportions with
a disproportionate increase in persons with superobesity,
defined as those with a BMI ≥50 kg/m2.
In 1991, the National Institutes of Health issued a
consensus statement concluding that in the morbidly obese,
bariatric surgery is the most successful intervention for
long-term weight loss [2]. Significant weight loss follow-
ing bariatric surgery reduces the inherent obesity-specific
comorbidities, lowers cardiovascular risk, and provides a
survival benefit in this escalating patient population [3,
4]. Weight loss surgery has become increasingly utilized,
with greater than 225,000 procedures performed in the
United States in 2008 according to the American Society of
Metabolic and Bariatric Surgery [5].
Due to the malabsorption induced by the procedure, in
conjunction with a reduced gastric volume and alterations
in eating behaviors, there is an increased risk of developing
certain mineral and vitamin deficiencies. Retinol deficiency
is more commonly associated with malabsorptive weight
loss surgical interventions, and fewer studies have reported

2Journal of Obesity
this outcome with Roux-en-Y gastric bypass surgery [6,7].
Routine postoperative laboratory surveillance at our insti-
tution identified a direct recurring coupling of deficiencies
of serum retinol and prealbumin concentration; this associ-
ation has not been previously described in the gastric bypass
literature.
2. Methods
We performed a retrospective chart review of 122 obese
patients (96 women, 26 men) who underwent Roux-en-
Y gastric bypass surgery at William Beaumont Hospital in
Royal Oak, Michigan, USA. Fifty-four charts had incomplete
data and were excluded from analysis; the remaining 69
subjects served as our study population. The patient popu-
lation was preapproved for surgery from a multidisciplinary
perspective at the William Beaumont Hospital Weight Con-
trol Center. The surgeries were performed between October
2005 and July 2007 by two affiliated bariatric surgeons. Data
were obtained from William Beaumont Hospital’s electronic
chart system (One Chart, EPIC systems Corporation) and
operative reports.
Serum markers of nutrition were assessed including:
prealbumin, albumin, total protein, and retinol. Roux limb
measurements were analyzed as a potential mediator of
malabsorption, and liver function studies were obtained.
Patients were interviewed at baseline and follow-up intervals
by our team of bariatric dietitians for nutritional compliance
with dietary protein intake. Confidentiality was protected by
assigning patients’ anonymous numbers, and the study was
approved by the hospital’s Human Investigation Committee.
3. Postoperative Treatment
Our protocol at the William Beaumont Hospital Weight
Loss Center involves regular follow-up outpatient visits at 6
weeks, 3, 6, 9, and 12 months with a multidisciplinary team
that includes a dietitian, exercise physiologist, psychologist,
and bariatrician. The dietitian works to optimize dietary
intake and assess for food intolerances. A comprehensive
nutritional intake routinely evaluates macronutrient com-
position. Routines recommendations include consuming a
higher daily intake of lean protein (approximately 1.2 g/kg
of ideal body weight), which generally corresponds to 55–
80 and 70–110 grams for women and men, respectively.
Other important dietary principles include avoidance of
excessive sugars (>5 grams per serving), which can promote
a Dumping Syndrome, and inclusion of <30% of daily intake
from fat per day to avoid steatorrhea. Patients are also coun-
seled to minimize the consumption of partially saturated
and hydrogenated fats. We routinely recommend a chewable
multivitamin twice daily, calcium citrate 500mg three times
daily with 400 IU of vitamin D, ferrous sulfate 30 mg daily
separated by 2 hours from the calcium compound, and
1000 mcg of cyanocobalamin daily to prevent vitamin and
mineral deficiencies. Laboratory surveillance of commonly
reported mineral and vitamin deficiencies as well as protein
levels prompted a tiered response of additional treatments as
needed.
Tab le 1: Baseline demographic variables.
Baseline
Mean age (yrs) 48.8±12.6
Female (%) 73.9
Weight (kg) 64.8±13.2
BMI (kg/m2)51.2±9.4
Roux limb length (cm) 113.6±33.1
4. Statistical Analysis
Demographics and baseline characteristics are reported as
means ±standard deviation (SD) or counts with percent
frequencies as appropriate. Spearman correlations were
completed between weight change and vitamin A levels
with all the continuous variables at both 6 weeks and 1
year. Univariate comparisons between patients meeting their
protein goal and those that did not were made using either
a test for normally distributed data or Wilcoxon rank tests
for the outliers. Categorical variables were examined using
Pearson’s chi-square as appropriate (expected frequency >5;
otherwise Fisher’s Exact tests were used). These same tests
were completed between patients with and without vitamin
A deficiency. Statistical significance was chosen at P≤.05.
All analyses used The SAS System for Windows version 9.2,
Cary, NC.
5. Results
Baseline demographic information of our study population
is in Table 1.Weightlossat6weeksand1yearfollowing
surgery was 20.1±9.1kg and 44.1±17.1kg, respectively
(Figure 1(a)). At 6 weeks and 1 year, 35% and 18% of patients
were vitamin A deficient (<325 mcg/L). Similarly, 34% and
19% had low prealbumin levels (<18 mg/dL) at these time
intervals (Figure 1(b)). Vitamin A directly correlated with
prealbumin levels at 6 weeks (r=0.67, P<.001), and 1-year
(r=0.67, P<.0001). There was no significant correlation
between roux length measurement and serum vitamin A
concentrations, at 6 weeks and 1 year (r=0.008 and −0.008,
resp.; P=.96 for both). Similarly, the correlations between
the roux length and prealbumin concentrations at 6 weeks or
1 year were insignificant (r=−0.08; P=.55 and r=−0.001;
P=.99). Achieving dietary protein intake goal, defined as
average daily dietary protein intake within 5 grams of intake
goal or greater on average, was also not associated with serum
levels of vitamin A at 6 weeks or 1 year (P=.41; P=.24,
resp.). No significant correlations between vitamin A levels
and markers of liver function (aspartate aminotransferase
and alanine aminotransferase) were observed at 6 weeks
(P=.29, .98, resp.) or at 1 year (P=.34, .99, resp.).
Vitamin K assessments were not included in the study
methodology and cannot be commented on. We exam-
ined the associations between zinc, protein, and vitamin
A in various forms and did not identify any significant
relationships.

Journal of Obesity 3
200
300
400
500
600
700
800
Vitamin A at 6 weeks
9 1011121314151617181920212223242526272829
Prealbumin at 6 weeks
(r=0.67, P<.001)
6 weeks
(a)
0
100
200
300
400
500
600
700
800
Vitamin A at 1 year
010203040
Prealbumin at 1 year
(r=0.67, P<.0001)
1year
(b)
Figure 1
6. Discussion
Vitamin A is an essential fat-soluble vitamin absorbed
through the small intestine as either retinol (animal derived)
or carotene (plant and vegetable derived). Subsequently, it
is converted to retinyl palmitate and hydrolyzed to bound
retinyl binding protein that transports vitamin A to tissues.
Several potential mechanisms may exacerbate vitamin A
deficiency in a postoperative gastric bypass patient. First,
the deficiency may arise from surgically bypassing the
duodenum and first portion of the jejunum, promoting
an iatrogenically induced malabsorption. Second, drastic
decreases in the dietary intake of many micronutrients
like carotenoids and retinol, especially in early recov-
ery, are likely to occur. In addition, traditional dietary
recommendations after gastric bypass include a low-fat
diet which potentially limit the absorption of fat-soluble
vitamins. This patient subset may also be at risk due to
confounding nonalcoholic steatohepatitis, higher rates of
cirrhosis, or both, which may interfere with maintaining
vitamin A storage and production. Finally, higher levels
of oxidative stress may also occur after gastric bypass
surgery, which can interfere with vitamin A absorption and
processing.
Vitamin A deficiency is rarely described in Western
society; however, worldwide, it remains the most common
etiology of visual disturbances, including blindness. Vita-
min A deficiency has been ascribed to a wide variety of
ophthalmologic complications including conjunctival and
corneal xerosis, keratomalacia, retinopathy, visual loss, and
nyctalopia. Moreover, retinol supports photosensitive pig-
mented cells of the retinal rods and cones that are necessary
for optimal visual acuity.
Serum retinol levels and protein-calorie malnutrition
have been correlated among children and infants in devel-
oping nations. Vitamin A deficient children treated with an
augmented dietary protein intake demonstrated an increase
in serum protein markers as well as serum retinol levels [8].
In this extreme clinical scenario, retinol deficiency was suc-
cessfully managed through this dietary intervention alone,
without the addition of vitamin A rich foods or vitamin
A supplementation [9]. The present findings support the
intimate interaction that serum retinol levels have to carrier
proteins which determine the bioavailability of serum retinol
concentration and reinforce the interdependent relationship
of these nutritional markers. As such, total body stores of
vitamin A may not be truly deficient; in reality, limited access
to nutritional protein binding and transport capacity may
underlie these serum retinol findings. These data suggest
that addressing the nutritional protein levels is necessary in
conjunction with deficient serum retinol concentrations.
There are several case series describing vitamin A defi-
ciency with visual disturbances involving patients who have
had gastric or intestinal surgery [6,7,10]. None of our
patients complained of visual disturbance; however, ocular
complaints may have been underreported in the scope of
this paper because many clinical features especially early in
the course of retinol deficiency can be vague or nonspecific
and may not have been recognized as clinically relevant.
Additionally, these variables were assessed over a relatively
short follow-up interval. It is important to acknowledge
this potential complication after bariatric surgery in patients
who undergo longstanding iatrogenic malabsorption with
limited nutritional protein stores [10] and consider appro-
priate diagnostic testing and referral for ophthalmologic
assessment, when appropriate.
7. Limitations
Our investigation has all the limitations of a small retro-
spective study. The study cohort was obtained via available
data. Accordingly, our population was limited to those
patients who were compliant with their baseline evaluation,
1-year follow-up exam and serial laboratory testing. Subjects
with missing preoperative or postoperative lab values were
excluded from the analysis, which may have biased our study
in representing a more compliant subset of patients. Because
we captured these data in the scope of clinical management,
multivitamin brands and additional retinol supplementation
may have varied according to patient preference and our
treatment methodology. We also did not account for other
potential confounding variables, including physical activity,
nutritional compliance, or the duration of supplementation.

4Journal of Obesity
Accordingly, we are not able to make treatment recom-
mendations for these deficiencies. Nevertheless, vitamin A
deficiency is of escalating interest in clinical centers and will
likely be the focus of future research. Finally, baseline vitamin
A levels were not obtained.
8. Conclusion
We noted a striking, direct relationship between postopera-
tive nutritional protein levels and vitamin A concentrations
in our gastric bypass populations. Vitamin A deficiency is
common after gastric bypass and is directly associated with a
low serum prealbumin concentration, a measure of protein-
calorie malnutrition. This fat-soluble vitamin deficiency
should be considered in postoperative patients and defi-
ciency should be strongly suspected in those with evidence
of protein calorie malnutrition. Improving awareness and
understanding of total body vitamin A utilization is of
paramount importance in the ongoing medical management
of this at-risk population.
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