Efficacy of Vitamin D Supplementation in Bariatric Surgery Patients
Efficacy of Vitamin D Supplementation in Bariatric Surgery Patients
As the use of bariatric surgery for treatment of extreme obesity adults continues to rise,
 clinicians must be aware of pre-existing nutritional deficiencies in overweight and obese
 patients. Nutritional deficiencies are common in patients undergoing bariatric surgery and
 these deficiencies should be detected and addressed early to avoid post-operative
 complications. To improve long-term outcomes following bariatric surgery, nutritional
 screening and prescribing appropriate supplementation to prevent nutrient deficiencies is
 needed. Vitamin D deficiency is common following bariatric surgery and has been reported to
 occur in 50-80% bariatric patients.The goal of this pilot study is to help develop nutrient
 supplementation interventions following two types of bariatric surgery: Roux-en Y gastric
 bypass and sleeve gastrectomy.

 Recently, several studies in adults have revealed an inverse relationship between body fat
 and blood 25-hydroxyvitamin D3 [25(OH)D] levels, the relevant marker of low vitamin D status.
 Although vitamin D is well known for its essential role in bone metabolism and calcium
 homeostasis, increasing evidence is linking vitamin D to obesity. This study will evaluate
 vitamin D status during post operative daily supplementation of 2,000 IU of vitamin D3 and
 1500 mg of calcium through assessment of changes in serum 25(OH)D, parathyroid hormone (PTH),
 calcium and phosphorus at baseline, 4 weeks, and 12 weeks following surgery. The dietary
 contribution of vitamin D and calcium will be estimated by food records analyzed using the
 University of Minnesota 2010 Nutrition Data System for Research (NDSR) program.

 Primary Hypothesis: Daily supplementation with 2,000 IU of vitamin D3 for 12 weeks will
 significantly increase mean serum 25(OH)D levels in obese subjects following bariatric
 surgery compared to baseline levels.

 Secondary Hypothesis: The percent response above baseline to daily supplementation with 2,000
 IU of vitamin D3 will significantly differ between Roux-en Y and sleeve gastrectomy patients.
The prospective pilot study is designed to evaluate vitamin D status pre-operatively and
 post-operatively in 37 female patients undergoing either Roux-en Y gastric bypass or sleeve
 gastrectomy at The Methodist Hospital with 32 patients expecting to complete the 12 week
 trial. Women scheduled for either of these two types of bariatric surgery will be considered
 for inclusion in the pilot study. Based on previous research experience at The Methodist
 Hospital, the majority of bariatric patients are women. No children are treated at the
 Methodist Hospital bariatric center.

 Subjects will be excluded if they have evidence of vitamin D deficiency (25(OH)D <20 ng/mL),
 hypercalcemia (calcium > 2.63 mmol/L), hypocalcemia (calcium < 1.75 mmol/L), renal
 insufficiency (GFR < 50 ml/min), or a history of primary hyperparathyroidism or renal tubular
 acidosis. Participants will be excluded if they take medications that interfere with vitamin
 D metabolism, have significant sun exposure, plan to travel to sunny climates during the
 study, or a history of hypercalcemia.

 Baseline measures of serum 25(OH)D, PTH, calcium and phosphorus will be obtained. Values will
 be determined one week prior to surgery and during the follow-up visit at 12 weeks
 postoperatively. In addition, 25(OH)D will be measured at the 4th week post-operative clinic
 visit. Baseline information obtained will include age, height (centimeter), weight
 (kilogram), body mass index, sex, and race or ethnicity. A full medication list and medical
 history to identify any co-morbid conditions will be collected. Participants will be
 instructed to avoid traveling to sunny locations during the 12 week study.

 Laboratory measurements pre-operative: 25(OH)D, PTH, CBC/Diff, glucose, calcium, albumin,
 total protein, sodium, potassium, CO2, BUN, creatinine, ALP, ALT, AST, bilirubin, lipid
 panel, ferritin, folate, iron, total iron binding capacity, hemoglobin A1c, insulin, vitamin
 B12, PT/PTT, TSH, HCG, C-reactive protein.

 Laboratory measurements at week 4: 25(OH)D

 Laboratory measurements at week 12: 25(OH)D, PTH, CBC/Diff, glucose, calcium, albumin, total
 protein, sodium, potassium, CO2, BUN, creatinine, ALP, ALT, AST, bilirubin, lipid panel,
 ferritin, folate, total iron binding capacity, vitamin B12, and TSH.

 Nutrient intake assessments: Dietary intake of macronutrients, vitamin D, calcium, and other
 micronutrients will be assessed using the University of Minnesota 2010 Nutrition Data System
 for Research (NDSR) program. NDSR is a comprehensive nutrient calculation software program
 used for research purposes. The NDSR database contains values for 160 nutrients and includes
 more than 18,000 foods.

 Participants' baseline laboratory will be used to measure the response to vitamin D and
 calcium supplementation over the course of 12 weeks. Bariatric patients participating in the
 study will be instructed to take a total of 1500 mg of calcium (as calcium citrate) plus 1000
 IU of vitamin D3 as three chewable tablets (Celebrate ®). An addition 1000 IU of vitamin D3
 per day will be taken as two chewable multi-vitamin bariatric supplements (Celebrate ®).
 Supplement compliance will be assessed by daily written records and inspection of supplement
 bottle containers at each clinic visit.

 Serum 25(OH)D will be measured by ARUP Laboratories (Salt Lake City, UT, USA) using a
 chemiluminescent immunoassay. Serum calcium and phosphorus will be determined by The
 Methodist Hospital Clinical Chemistry Department as part of the standard bariatric protocol
 comprehensive metabolic panel. Intact PTH (iPTH) assays will be performed using the ADVIA
 Centaur ® XP Immunoassay System.

 Vitamin D deficiency will be defined as 25(OH)D levels less than 20 ng/mL (50 nmol/L) and
 vitamin D insufficiency as 21 to 29 ng/mL (50 to 80 nmol/L). Secondary hyperparathyroidism
 will be defined as iPTH ≥ 70 ng/L. An increase in serum intact PTH level will be taken to be
 indicative of a possible negative calcium balance or a vitamin D deficiency (or both).
 Hypercalcemia will be defined as calcium > 2.63 mmol/L.

 Statistical analysis:

 Primary Hypothesis: Daily supplementation with 2,000 IU of vitamin D3 for 12 weeks will
 significantly increase mean serum 25(OH)D levels in obese subjects following bariatric
 surgery compared to baseline levels.

 Secondary Hypothesis: The percent response above baseline to daily supplementation with 2,000
 IU of vitamin D3 will significantly differ between Roux-en Y and sleeve gastrectomy patients.

 Subject Withdrawal:

 Participants will be withdrawn from the study if serum 25(OH)D levels are identified as
 within the deficient range so that the patient can receive needed treatment. A vitamin D
 deficiency will be defined as 25(OH)D concentrations less than 20 ng/mL (50 nmol/L) and
 vitamin D insufficiency as 21 to 29 ng/mL. In addition, if an abnormally high level of
 25(OH)D is obtained (200 ng/mL or 500 nmol/L), we will have the 25(OH)D measurement repeated.
 If the second test is confirmed to be high, then we will withdraw that particular patient
 from the study for medical follow-up. If we find a trend of excess vitamin D among
 participants, however, we will re-evaluate and consider termination of the study.
Inclusion Criteria: Adult female obese patients undergoing either Roux-en Y gastric bypass
 or sleeve gastrectomy at The Methodist Hospital may participate in the study. Obese
 patients with a body mass index (BMI) > 40 or BMI >35 with a co-morbidity will be eligible.

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 Exclusion Criteria:Subjects will be excluded if they have evidence of vitamin D deficiency
 (< 20 ng/mL), hypercalcemia (calcium > 2.63 mmol/L), hypocalcemia (calcium < 1.75 mmol/L),
 renal insufficiency (GFR < 50 ml/min), or a history of primary hyperparathyroidism or renal
 tubular acidosis.Participants will be excluded if they take medications that interfere with
 vitamin D metabolism, have significant sun exposure, plan to travel to sunny climates
 during the study, or a history of hypercalcemia.

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