Vitamin D Deficiency in the Morbidly Obese

Although vitamin D deficiency has been well-documented following gastric bypass surgery, there are few studies of vitamin D status in the non-operative morbidly obese patient. We examined 25-hydroxyvitamin D (25-OHD) levels in 60 morbidly obese pre-operative females; 62% of them had 25-OHD levels below normal range (16-74 ng/ml) which were not associated with reductions in serum calcium or phosphorus, liver or kidney dysfunction, and were not significantly correlated to patients' age. However, 25-OHD levels were significantly (p < 0.0001) and negatively correlated to body mass (r = -0.49). These data suggest that low vitamin D may be associated with obesity per se. Hypovitaminosis D, when it is found in post-bariatric surgery patients, may not be caused by the surgery since it may have been present to some degree pre-operatively.     

Evaluation of markers for calcium homeostasis in a population of obese adults undergoing gastric bypass operations

BACKGROUND: Gastric bypass operation has become a very common procedure for treatment of obesity. Changes in calcium absorption can result in changes in total body calcium, parathyroid hormone (PTH), and vitamin D levels. There is little known about the longterm effects of Roux-en-Y gastric bypass on calcium metabolism and bone homeostasis. STUDY DESIGN: Between January 2000 and January 2006, 535 morbidly obese patients underwent standard Roux-en-Y gastric bypass. All patients were given a standard multivitamin, vitamin D, and calcium supplement starting on day 12 after the operation. Metabolic parameters, such as serum calcium levels, vitamin D, and PTH, both pre- and postoperatively, were measured and compared at several intervals. RESULTS: Four-hundred and forty-four patients were followed for a minimum of 2 years. No statistical significance was found between the pre- and postoperative serum levels of calcium and vitamin D, although vitamin D levels generally increased during the first year after operation. Serum levels of PTH were substantially higher at 18 and 44 weeks after the operation. CONCLUSIONS: Hypocalcemia did not develop in any patients during the postoperative period. Increased PTH levels were observed after gastric bypass operation. This can result in calcium mobilization of calcium from the skeleton and increased renal calcium reabsorption. Total body calcium depletion could occur from bone mobilization, if longterm calcium supplementation is not maintained. Vitamin D supplementation can assist in prevention of bone calcium depletion.     

Markers of Bone and Calcium Metabolism Following Gastric Bypass and Laparoscopic Adjustable Gastric Banding

BACKGROUND: Several studies have suggested that morbid obesity is associated with vitamin D deficiency and elevated parathyroid hormone (PTH). Studies have also suggested that there is an increase in vitamin D deficiency, bone resorption, and elevated PTH after gastric bypass surgery. Few studies have evaluated markers of bone and calcium metabolism after laparoscopic adjustable gastric banding or compared these results to those after gastric bypass. METHODS: Data on all patients undergoing primary gastric bypass (GBP; n = 979) and laparoscopic adjustable gastric banding (LAGB; n = 269) procedures at a tertiary-referral center from June 1996 through March 2005 were reviewed from a prospective database. Only patients with 25OH vitamin D levels available were included in this study (n = 534; GBP = 403, LAGB = 131). All patients were advised to take at least 1,200 mg calcium and 800-1,200 IU of vitamin D daily before and subsequent to their operation. Markers for bone metabolism [25OH Vitamin D, corrected serum calcium, alkaline phosphatase (AP), and PTH] were evaluated preoperatively and 3, 6, 12, and 24 months postoperatively. An analysis of variance and chi-square were performed to determine differences between the operative groups. Linear regression analysis was performed to evaluate the relationship between preoperative body mass index (BMI) and 25OH vitamin D and PTH levels and between percent excess weight loss and 25OH vitamin D and PTH after surgery. RESULTS: Sixty-four percent of all patients presented with vitamin D deficiency (<20 ng/ml) and 14% presented with elevated PTH preoperatively. Mean 25OH vitamin D levels and AP levels increased significantly after GBP surgery (vitamin D, 17 to 25 ng/ml 12 months post-op; AP, 80 to 90 IU/L 24 months post-op). Corrected calcium levels remained within normal limits and showed no change over time after both procedures. AP levels significantly increased from 76 IU/l preoperatively to 82 IU/l 6 months after LAGB surgery and then decreased to 59 IU/l 24 months after LAGB surgery. Linear regression analysis of preoperative vitamin D, PTH, and BMI values showed a significant positive relationship between initial BMI and PTH (r = 0.29) and a significant negative relationship between vitamin D and initial BMI (r = -0.19). A significant positive linear relationship between vitamin D and percent excess weight loss was evident 12 and 24 months after GBP surgery (r = 0.39 and 0.57, respectively). A negative relationship was evident between PTH and vitamin D 6 months after GBP surgery (r = -0.35) and 12 months after LAGB surgery (r = -0.61). CONCLUSIONS: These findings suggest that morbid obesity is associated with vitamin D deficiency, and elevated PTH and with adequate supplementation, GBP, and particularly LAGB, patients can improve their bone metabolism abnormalities related to obesity. Furthermore, adequate supplementation for GBP patients may attenuate the increased risk for bone loss associated with malabsorption from the bypass.     

Effect of gastric bypass surgery on vitamin D nutritional status

BACKGROUND: We previously reported a 60% prevalence of vitamin D (VitD) depletion, defined as a 25-hydroxyvitamin D (25-OHD) level of < or =20 ng/mL, in morbidly obese patients preoperatively. We now report the effect of gastric bypass (GB) on the VitD nutritional status in these patients. METHODS: We prospectively studied 108 morbidly obese patients who had undergone GB. Routine postoperative supplementation consisted of 800 IU VitD and 1500 mg calcium daily. Serum calcium, parathyroid hormone, and 25-OHD were measured before and 1 year after GB. RESULTS: The mean patient age was 46 +/- 9 years, 93% were women, and 72% were white. Preoperatively and at 1 year postoperatively, the prevalence of VitD depletion and hyperparathyroidism (HPT) and the mean 25-OHD level was 53% and 44%, 47% and 39%, and 20 and 24 ng/mL, respectively. One year after GB, the percentage of excess weight loss was 67% and demonstrated significant correlations both positively with 25-OHD and inversely with parathyroid hormone. At both intervals, blacks had a greater incidence of VitD depletion than did whites, and, at 1 year after GB, HPT was more common in patients with VitD depletion (55% versus 26%, P = .002). CONCLUSION: With customary supplementation, VitD nutrition is improved after GB, but VitD depletion persists in almost one half of patients, and blacks are at a significantly greater risk than whites. HPT did not improve, and those with VitD depletion had a significantly greater rate of HPT. Additional prospective studies are needed to determine how to optimize VitD nutrition and avoid potential long-term skeletal complications after GB.     

Treatment of vitamin D depletion after Roux-en-Y gastric bypass: a randomized prospective clinical trial

BackgroundA high prevalence (60%) of vitamin D (VitD) depletion, defined as a serum 25-hydroxyvitamin D level of ≤20 ng/mL, is present in preoperative morbidly obese patients. Despite daily supplementation with 800 IU VitD and 1500 mg calcium after Roux-en-Y gastric bypass (RYGB), VitD depletion persists in almost one half (44%) of patients. However, the optimal management of VitD depletion after RYGB and the potential benefits of such treatment are currently unknown.MethodsA total of 60 VitD-depleted morbidly obese women were randomly assigned to receive 50,000 IU of VitD weekly after RYGB (group 1; n = 30) or no additional VitD after RYGB (group 2; n = 30). All patients received a daily supplement of 800 IU VitD and 1500 mg calcium. The serum calcium, parathyroid hormone, 25-hydroxyvitamin D, bone-specific alkaline phosphatase, urinary N-telopeptide, and bone mineral density were measured preoperatively and 1 year after RYGB. Questionnaires were used to assess other potential sources of VitD, including sunlight exposure and ingestion of VitD-containing foods/liquids.ResultsAt 1 year after RYGB, VitD depletion and mean 25-hydroxyvitamin D level had improved significantly in group 1 (14% and 37.8 ng/mL, respectively) compared with the values in group 2 (85% and 15.2 ng/mL, respectively; P <.001 for both). A significant 33% retardation in hip bone mineral density decline (P = .043) and a significantly greater resolution of hypertension was seen in group 1 (75% versus 32%; P = .029). No significant adverse effects were encountered from pharmacologic VitD therapy.ConclusionThe results of our study have shown that 50,000 IU of VitD weekly after RYGB safely corrects VitD depletion in most women, attenuates cortical bone loss, and improves resolution of hypertension.     

Risk of secondary hyperparathyroidism after laparoscopic gastric bypass surgery in obese women

Background Metabolic bone disease is a potential complication of bariatric surgery. The aims of our study were to evaluate the effects of laparoscopic gastric bypass on calcium and vitamin D metabolism, and to identify patients at high risk to develop secondary hyperparathyroidism (HPT). Methods Serum calcium, alkaline phosphatase, intact parathyroid hormone (PTH), and 25-hydroxy (OH) vitamin D were measured at 3, 6, 12, and 24 months after laparoscopic gastric bypass in a cohort of morbidly obese women. Logistic regression was used in both univariate and multivariate models to identify independent preoperative variables associated with secondary HPT. Results The study enrolled 193 morbidly obese women. During the 2-year follow-up period, the incidence of elevated PTH levels (>65 pg/ml) was 53.3%. The mean time elapsed between surgery and detection of secondary HPT was 9.1 months (range, 3–24 months). Vitamin D deficiency was observed in 39 patients (20.2%). On univariate analysis, the preoperative factors associated with secondary HPT were race (high PTH levels were detected in 70% of African Americans versus 50% of Caucasians; p < 0.05), preoperative body mass index (BMI; high PTH: 52.5 ± 10.8 versus normal PTH: 48.9 ± 7.5 kg/m²; p < 0.01), and age (high PTH: 44.9 ± 9.2 versus normal PTH: 42.3 ± 9 years, p < 0.05). Race and age remained independent risk factors for secondary HPT in the multivariate logistic regression model after adjusting for the covariate Roux-limb length. African Americans were at more than 2.5 times greater risk to develop secondary HPT as Caucasian (RR 2.5; 95% CI: 1.03–6.17, p < 0.05). Patients older than 45 years were at 1.8 times higher risk of developing secondary HPT as their younger counterparts (RR 1.8; 95% CI: 1.01–3.32, p < 0.05). Conclusions Morbidly obese women have a high incidence of elevated PTH levels after gastric bypass surgery. Low vitamin D levels did not constitute the only reason behind this finding. African-American women and women older than 45 years of age were at significantly higher risk of developing secondary HPT. In these populations, aggressive supplementation with calcium citrate and vitamin D should be implemented.     

Prevalence of vitamin D depletion among subjects seeking advice on osteoporosis: a five-year cross-sectional study with public health implications

Summary We assessed vitamin D nutritional status in unselected consecutive patients seeking advice on osteoporosis. The prevalence of vitamin D depletion ranged from 15–72% depending upon the cut-off levels used for serum 25-hydroxyvitamin D, and the prevalence did not change over the 5 years of the study. Introduction Vitamin D depletion is a significant public health problem and has been studied in different populations using different cut-off levels, but the optimal level is yet to be established. Methods In a cross-sectional study of 2924 patients seen for osteoporosis advice we determined the prevalence of vitamin D depletion, as assessed by 25-hydroxyvitamin D (25-OHD), using three different cut-off levels stratified by gender, race and the year of the study over 5 years. Results Mean age was 68.3 ± 10.0 years; 90% women and 88% white. Mean 25-OHD level was 24.6 ± 10 ng/ml and mean PTH was 48.4 ± 32 pg/ml. The prevalence of vitamin D depletion was 15% with a cut-off level of <15 ng/ml, and rose to 32% and 72% with cut-off levels <20 ng/ml and <30 ng/ml, respectively. The prevalence was higher in men and blacks and remained constant over 5 years, regardless of the cut-off level. The expected inverse relationship between 25-OHD and PTH was observed irrespective of gender or ethnicity. Conclusions The prevalence of vitamin D depletion in patients seeking advice for osteoporosis is high and did not change over the 5 years of the study.     

Vitamin D Supplementation Efficacy: Sleeve Gastrectomy Versus Gastric Bypass Surgery

Background

Vitamin D deficiency is common with bariatric surgery, and few prospective studies comparing different surgical procedures have evaluated appropriate vitamin D supplementation levels. Therefore, vitamin D₃ and calcium supplementation were evaluated following gastric bypass and sleeve gastrectomy.

Methods

Women consumed 2,000 international units (IU) of vitamin D₃ and 1,500 mg calcium citrate daily for 3 months following gastric bypass (n?=?11) and sleeve gastrectomy (n?=?12). Height, weight, body mass index (BMI), serum 25-hydroxyvitamin D [25(OH)D], and serum PTH concentrations were measured preoperatively and at 3 months. Wilcoxon signed rank analyses compared body weight parameters, serum 25(OH)D and PTH concentrations, and dietary intakes of vitamin D and calcium preoperatively and at 3 months. Vitamin D deficiency was defined as a serum 25(OH)D concentration <20 ng/mL (50 nmol/L).

Results

Vitamin D deficiency decreased from 60.6 % preoperatively to 26.1 % after 3 months (P?P?Conclusions Reduced food intake increased the risk of vitamin D deficiency following bariatric surgery. However, daily supplementation with 2,000 IU of vitamin D₃ and 1,500 mg calcium citrate significantly increased 25(OH)D concentrations and reduced the percent of women who were vitamin D deficient. Although serum 25(OH)D concentrations did not reach levels associated with detrimental health effects, several women remained vitamin D deficient and more aggressive supplementation may be indicated.     

Unchanged Hypovitaminosis D and Secondary Hyperparathyroidism in Morbid Obesity after Bariatric Surgery

Background: Morbidly obese patients have been reported to present with vitamin D insufficiency and secondary hyperparathyroidism. We assessed whether bariatric surgery alters the 25-hydroxyvitamin D (calcidiol) and intact parathyroid hormone (iPTH) levels in patients presenting with morbid obesity. Methods: A cross-sectional survey was conducted on 144 patients of whom 80 had not undergone bariatric surgery, while 64 had bariatric surgery at a mean of 36 months previously. Calcidiol levels were defined as being normal (>50 nmol/L), insufficient (2550 nmol/L) and deficient (<25 nmol/L). Mild secondary hyperparathyroidism was defined as iPTH >7.3 pmol/L with simultaneous normal values for creatinine, calcium and phosphorus. Results: 80% of the patients presented low vitamin D levels and mild secondary hyperparathyroidism. Previous surgery or the presence of diabetes did not influence calcidiol levels. Corrected serum calcium, phosphorus, alkaline phosphatase, iPTH and Calcidiol were similar between subjects with and without surgery. Conclusions: Vitamin D deficient states with secondary hyperparathyroidism in the morbidly obese precede and are not significantly affected by bariatric surgery. Hypovitaminosis D with secondary hyperparathyroidism due to low calcidiol bio-availability should be added to the crowded list of sequelae of morbid obesity. While further studies are warranted, it seems advisable to support vitamin D supplementation in the morbidly obese population.     

Effects of Bariatric Surgery on Vitamin D Status and Secondary Hyperparathyroidism: A Prospective Study

Background: Morbidly obese patients have been reported to present with vitamin D insufficiency and secondary hyperparathyroidism. Scattered data are available regarding the effects of bariatric surgery on vitamin D status. We studied calcium metabolism and vitamin D status before and after bariatric surgery. Methods: In this prospective study, 64 patients (M5/F59) fulfilled the inclusion criteria (i.e. 2 calcidiol serum determinations in the winter season) among 457 morbidly obese individuals who underwent Roux-en-Y gastric bypass (RYGBP) a mean of 36 months previously. Laboratory data (serum calcium, phosphorus, creatinine, alkaline phosphatase, albumin, calcidiol, albumin and iPTH) were determined before and after RYGBP. Pre- and postoperative calcidiol levels were categorized as being normal (>50 nmol/L), insufficient (25-50 nmol/L), and deficient (<25 nmol/L). Pre- and postoperative mild secondary hyperparathyroidism was defined as iPTH >7.3 pmol/L with simultaneous normal values for creatinine, calcium and phosphorus. Results: RYGBP produced a significant weight loss coupled with a simultaneous increase in calcidiol (+28%, P<0.0005) and decrements in total alkaline phosphatase (-53%, P<0.0005) and iPTH (-74%, P=0.001). Corrected serum calcium, phosphorus, and creatinine levels were indistinguishable before and after RYGBP. Additionally, 37.5% of the patients maintained their calcidiol category, while 42.2 % improved it and 20.3% lost one category. Conclusions: RYGBP does not completely correct pre-existing vitamin D deficient states with secondary hyperparathyroidism. Low calcidiol bioavailability and or insufficient sunlight exposure do probably persist after bariatric surgery. While randomized controlled studies are warranted, it seems advisable to support vitamin D supplementation as well as increasing sunlight exposure in the morbidly obese population.     

Prevalence of Vitamin D Insufficiency and Deficiency in Morbidly Obese Patients: A Comparison with Non-Obese Controls

Background Vitamin D deficiency is common in patients after bariatric surgery. However, obesity itself has also been associated with decreased vitamin D. The prevalence of vitamin D deficiency in obese persons has not previously been compared to non-obese controls when controlling for factors that could affect vitamin D status. Methods We evaluated 25 hydroxy vitamin D, iPTH, calcium, albumin, and creatinine in 41 patients undergoing Roux-en-Y gastric bypass. We then compared them to healthy non-obese controls matched for age, sex, race/ethnicity, and season of vitamin D measurement. Results Ninety percent of the pre-bariatric surgery patients had 25-OH-D levels <75 nmol/l, and 61% had 25-OH-D levels <50 nmol/l versus 32 and 12% in controls, respectively. Additionally, 49% of the pre-bariatric surgery patients had secondary hyperparathyroidism versus 2% of controls. These differences persisted after controlling for sunlight exposure and dietary intake of calcium and vitamin D. Mean calcium, corrected for albumin, and creatinine were not significantly different between the groups, but mean albumin levels were significantly lower among surgery patients. Conclusion Vitamin D deficiency is common in obese patients at the time of bariatric surgery and is also accompanied by secondary hyperparathyroidism approximately half the time. These findings suggest that vitamin D deficiency after bariatric surgery is multifactorial and in part caused by preoperative vitamin D deficiency rather than postoperative malabsorption alone. In this study, increased vitamin D deficiency in obese persons cannot be explained by a difference in calcium/vitamin D intake or sunlight exposure.     

Secondary Hyperparathyroidism, Vitamin D Sufficiency, and Serum Calcium 5 Years After Gastric Bypass and Duodenal Switch

Background

The prevalence of secondary hyperparathyroidism (SHPT) is high after bariatric surgery. Vitamin D is supplied to counteract SHPT and bone disease, and we studied vitamin D associations with SHPT.

Methods

We measured serum levels of 25-OH vitamin D and parathyroid hormone (PTH) 5 years after gastric bypass and duodenal switch. One hundred twenty-five patients were included, of whom 114 (91 %) had undergone gastric bypass and 11 (9 %) had undergone duodenal switch. SHPT was defined as PTH?>?7.0 pmol/l in the absence of hypercalcemia. 25-OH vitamin D levels were divided into three categories: <50, 50–74, and ≥75 nmol/l. Serum ionized calcium, magnesium, phosphate, and creatinine were divided into tertiles.

Results

Mean age?±?SD was 44?±?9 years at 5 years follow-up. Ninety out of 125 (72 %) patients were women. SHPT was present in 45 out of 114 (40 %) gastric bypass patients and in 11 out of 11 (100 %) duodenal switch patients. The prevalence was high in all vitamin D categories studied. An inverse association between ionized calcium and PTH was found. For the gastric bypass patients, the odds ratio for SHPT in the upper two tertiles of ionized calcium was 0.35; 95 % CI, 0.15–0.79; p?=?0.011, compared with the lowest tertile. Supplements of vitamin D and calcium were not associated with a lower prevalence of SHPT at 5 years follow-up.

Conclusions

The prevalence of SHPT was high 5 years after gastric bypass and duodenal switch. SHPT was inversely associated with serum ionized calcium, but not with vitamin D. The supplementation used was insufficient to compensate for the impaired calcium absorption after surgery.     

High prevalence of vitamin D insufficiency in a United Kingdom urban morbidly obese population: Implications for testing and treatment

BackgroundCurrent recommendations suggest universal screening of vitamin D status before bariatric surgery to identify individuals at risk for postoperative deficiency. However little is known about the magnitude or severity of vitamin D insufficiency in the morbidly obese population awaiting bariatric surgery in the United Kingdom. The purpose of this prospective observational study was to assess the prevalence and determinants of vitamin D insufficiency in an urban multiethnic U.K. population awaiting bariatric surgery.MethodsConsecutive patients attending a morbid obesity service were comprehensively assessed using a recognized obesity staging tool. Data collected included 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), corrected calcium (Ca²⁺), body mass index (BMI), and the presence and severity of obesity associated co-morbidities, including type 2 diabetes (T2 DM), cardiovascular disease (CVD), depression, obstructive sleep apnea (OSA), and functional limitation.ResultsOf the 118 patients assessed, 79% were female, and 21% were male, with BMI of 52.6±9.4 kg/m² (mean±standard deviation) and mean age of 44±11 years. Twenty-four percent had T2 DM, 28% CVD, 31% OSA, and 21% depression. Vitamin D insufficiency was found in 90% of the population, with a median serum 25(OH)D of 8.8 ng/mL. Secondary hyperparathyroidism was present in 43% of those with vitamin D insufficiency. Risk was not influenced by ethnicity, age, or gender. However severe functional limitation was associated with lower vitamin D status.ConclusionRegardless of ethnicity, vitamin D insufficiency appears to be typical among this clinic population; therefore, routine vitamin D supplementation is suggested for all individuals awaiting bariatric surgery rather than testing vitamin D status in an attempt to identify high-risk individuals.     

Vitamin D Status 10 Years After Primary Gastric Bypass: Gravely High Prevalence of Hypovitaminosis D and Raised PTH Levels

Background

The primary aim of this study was to evaluate the prevalence of vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass. Secondly, we have tried to assess predictors for vitamin D deficiency.

Methods

Five hundred thirty-seven patients who underwent primary Roux-en-Y gastric bypass surgery between 1993 and 2003 at the Örebro University Hospital and Uppsala University Hospital were eligible for the study. Patients were asked to provide a blood sample between November 2009 and June 2010 and to complete a questionnaire about their postoperative health status. Serum values of 25-OH vitamin D, parathyroid hormone (PTH), alkaline phosphatase (ALP) and calcium were determined.

Results

Follow-up was completed in 293 patients, of which 83 % were female, with an age of 49?±?9.9 years after a median time of 11?±?2.8 years. Vitamin D, PTH and albumin-corrected calcium values were 42?±?20.4 nmol/L, 89.1?±?52.7 ng/L and 2.3?±?0.1 mmol/L, respectively. Of all patients, 65 % were vitamin D deficient, i.e. 25-OH vitamin D <50 nmol/L, and 69 % had PTH above the upper normal reference range, i.e. >73 ng/L. Vitamin D was inversely correlated with PTH levels (p?<?0.001) and positively correlated with calcium (p?=?0.016). Vitamin D did not correlate with ALP. The only factor found to predict vitamin D deficiency was high preoperative body mass index (BMI) (p?=?0.008), whereas gender, age, time after surgery and BMI at follow-up did not.

Conclusions

Vitamin D deficiency and secondary hyperparathyroidism after Roux-en-Y gastric bypass (RYGB) were confirmed in our study because 65 % of patients had vitamin D deficiency, and 69 % had increased PTH levels more than 10 years after surgery. These data are alarming and highlight the need for improved long-term follow-up. Vitamin D deficiency does not seem to progress with time after surgery, possibly due to weight loss. Only preoperative BMI, cutoff point 43 kg/m², was a predictor of vitamin D deficiency at follow-up. Improved long-term follow-up of patients that undergo RYGB is needed.     

The long-term effects of gastric bypass on vitamin D metabolism

OBJECTIVE: Alterations of the endocrine system in patients following Roux-en-Y gastric bypass (GBP) are poorly described and have prompted us to perform a longitudinal study of the effects of GBP on serum calcium, 25-hydroxy-vitamin-D (vitamin D), and parathyroid hormone (PTH). METHODS: Prospectively collected data were compiled to determine how GBP affects serum calcium, vitamin D, and PTH. Student t test, Fisher exact test, or linear regression was used to determine significance. RESULTS: Calcium, vitamin D, and PTH levels were drawn on 243 patients following GBP. Forty-one patients had long-limb bypass (LL-GBP), Roux >100 cm, and 202 had short-limb bypass (SL-GBP), Roux < or =100 cm. The mean (+/-SD) postoperative follow-up time was significantly longer in the LL-GBP group (5.7 +/- 2.5 years) than the SL-GBP group (3.1 +/- 3.6 years, P < 0.0001). When corrected for albumin levels, mean calcium was 9.3 mg/dL (range, 8.5-10.8 mg/dL), and no difference existed between LL-GBP and SL-GBP patients. For patients with low vitamin D levels (<8.9 ng/mL), 88.9% had elevated PTH (>65 pg/mL) and 58.0% of patients with normal vitamin D levels (> or =8.9 ng/mL) had elevated PTH (P < 0.0001). In individuals with vitamin D levels <30 ng/mL, 55.1% (n = 103) had elevated PTH, and of those with vitamin D levels > or =30 ng/mL 28.5% (n = 16) had elevated PTH (P = 0.0007). Mean vitamin D levels were lower in patients who had undergone LL-GBP as opposed to those with SL-GBP, 16.8 +/- 10.8 ng/mL versus 22.7 +/- 11.1 ng/mL (P = 0.0022), and PTH was significantly higher in patients who had a LL-GBP (113.5 +/- 88.0 pg/mL versus 74.5 +/- 52.7 pg/mL, P = 0.0002). There was a linear decrease in vitamin D (P = 0.005) coupled with a linear increase in PTH (P < 0.0001) the longer patients were followed after GBP. Alkaline phosphatase levels were elevated in 40.3% of patients and correlated with PTH levels. CONCLUSION: Vitamin D deficiency and elevated PTH are common following GBP and progress over time. There is a significant incidence of secondary hyperparathyroidism in short-limb GBP patients, even those with vitamin D levels > or =30 ng/mL, suggesting selective Ca malabsorption. Thus, calcium malabsorption is inherent to gastric bypass. Careful calcium and vitamin D supplementation and long-term screening are necessary to prevent deficiencies and the sequelae of secondary hyperparathyroidism.     

Calcium Metabolism in Pre- and Postmenopausal Morbidly Obese Women at Baseline and After Laparoscopic Roux-En-Y Gastric Bypass

Background: The authors evaluated calcium metabolism in obese women, before and after menopause, at baseline and at 6 and 12 months after laparoscopic Roux-en-Y gastric bypass (LRYGBP). LRYGBP restricts food intake and produces physiological changes that may be similar to those after high Billroth II subtotal gastrectomy. Methods: Serum calcium (Ca), phosphate, bone-specific alkaline phosphatase (BSAP) and 25-hydroxyvitamin D3 (25-OH D) were measured at baseline and 12 months after LRYGBP. Urinary N-telopeptide (u-NTX) was measured at baseline and serum C-telopeptide (s-CTX) at 6 and 12 months after LRYGBP. Parathormone (PTH) was measured at baseline and 6 and 12 months after LRYGBP. Patients were divided into 2 groups: Group I (n=30) pre-menopausal women aged 18-42 y, and Group II (n=30) post-menopausal women aged 40-71 y. Patients with renal, hepatic, metabolic and bone disease, smoking women, as well as patients with u-NTX values at baseline >67 nMBCE/mMCr were excluded. Results: At baseline, PTH was elevated in 10% of patients in each group, correlated positively with BMI, and low serum calcium values were found in 30% of Group I and 16.7% of Group II. High values of serum C-telopetide were seen in Group I at 6 months after surgery and in Group II 12 months after LRYGBP. Group II showed a greater increase in BSAP at 12 months after LRYGBP. 25-0H D decreased in both groups, and a progressive increase in PTH was observed. Serum calcium did not change in both groups. Conclusion: Calcium metabolism is altered in pre- and post-menopausal women following LRYGBP. Calcium and vitamin D supplementation is strongly advised in all patients.     

Correction of preoperative vitamin D deficiency after Roux-en-Y gastric bypass surgery

BACKGROUND: To evaluate the adequacy of supplementation to correct preoperative vitamin D deficiency in adult patients during the year after Roux-en-Y gastric bypass (RYGB) surgery. METHODS: The medical records were reviewed and the preoperative and 12-month postoperative serum 25-hydroxyvitamin D [25(OH)D] levels were compared in patients who underwent RYGB from 2002 to 2004. The serum 25(OH)D levels were defined as being optimal (> or = 80 nmol/L), suboptimal (50-79 nmol/L), or deficient (<50 nmol/L). Patients with deficient 25(OH)D levels were prescribed 50,000 IU ergocalciferol weekly. The remaining patients averaged 710 IU supplemental vitamin D intake daily. RESULTS: The mean patient age was 43.8 +/- 10.7 years, and the mean preoperative body mass index was 51.8 +/- 9.8 kg/m2. Of the 95 patients with baseline and 12-month 25(OH)D levels, 89% were women. The mean preoperative 25(OH)D level was 49.7 +/- 26.5 nmol/L; 34% had suboptimal 25(OH)D levels and 54% had deficient levels before surgery. Twelve months after surgery, those receiving 50,000 IU weekly (n = 40) had a mean 25(OH)D level of 69.2 +/- 22.2 nmol/L; 63% had suboptimal and 8% deficient levels. Those taking 710 IU daily (n = 55) had a mean 25(OH)D level of 85.5 +/- 33.0 nmol/L; 44% had suboptimal and 6% deficient levels. CONCLUSION: Vitamin D deficiency is prevalent in RYGB patients before surgery. The vitamin D status improved markedly after RYGB surgery with either 710 IU vitamin D daily or 50,000 IU weekly. Current supplementation practices do not appear to optimize the serum 25(OH)D levels and need to be more closely examined.     

Calcium Metabolism in the Morbidly Obese

Background: Morbidly obese patients are known to have abnormal calcium metabolism compared with the non-obese, but the clinical significance of this is unknown. Since surgical treatment of obesity may itself cause hyperparathyroidism, it is important to understand the preoperative physiology of these patients. Methods: 213 consecutive patients (M 37 : F 176, ages 21-68) presenting for surgical treatment of morbid obesity between October 2000 and June 2002 were prospectively evaluated. Preoperative levels of serum calcium corrected for albumin, alkaline phosphatase, parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured. We recorded the prevalence of abnormalities in study parameters and correlated them with PTH levels. Results: Hyperparathyroidism (PTH >65 pg/ml) was present in 25.0% of subjects. By contrast, abnormalities of serum calcium were rare. The prevalence of hypocalcemia was 3.5%, and of hypercalcemia was 0.5%. Only 4.3% of patients had increased levels of alkaline phosphatase. 21.1% of patients had abnormally low levels of 25-hydroxyvitamin D (median 15 ng/ml), and 23.1% had increased levels of 1,25-dihydroxyvitamin D (median 49 pg/ml). PTH was positively correlated with BMI (r=.30, P=<.001) and 25-dihydroxyvitamin D (r=.27, P=.01), and was negatively correlated with alkaline phosphatase (r=.21, P=.02). There was no correlation between PTH and calcium, 1,25-dihydoxyvitamin D, age, or sex. Conclusions: Parathyroid hormone levels are increased in the morbidly obese and are positively correlated with BMI. Recognition of preoperative hyperparathyroidism is important because of the risk of attributing postoperative hyperparathyroidism to the effects of surgery. Further studies are needed to elucidate the cause of elevated PTH in these patients.     

Vitamin D depletion impairs hypertension resolution after Roux-en-Y gastric bypass

BACKGROUND: Morbid obesity is a risk factor for hypertension (HTN) and vitamin D (VitD) depletion. Gastric bypass (GBP) resolves HTN in many patients. The goal of this study was to evaluate the potential role of VitD nutritional status on HTN resolution in patients undergoing GBP. METHODS: A retrospective review of morbidly obese patients taking antihypertensive medications and undergoing GBP from September 1, 2002, through February 28, 2006 was performed. RESULTS: At 1 year postoperatively HTN resolved in 53%, improved in 36%, and was unchanged in 11%. Sex, race, body mass index, and percentage of excess weight loss did not impact HTN resolution. Younger patients experienced a greater rate of HTN resolution. Patients with VitD depletion had significantly lower rates of HTN resolution compared to those with adequate levels of VitD (42% vs 61%; P = .008). CONCLUSIONS: VitD nutritional status impacts the resolution rate of HTN after GBP. All morbidly obese patients undergoing GBP should be monitored and treated for VitD depletion.     

Correction of preoperative vitamin D deficiency after Roux-en-Y gastric bypass surgery

BackgroundTo evaluate the adequacy of supplementation to correct preoperative vitamin D deficiency in adult patients during the year after Roux-en-Y gastric bypass (RYGB) surgery.MethodsThe medical records were reviewed and the preoperative and 12-month postoperative serum 25-hydroxyvitamin D [25(OH)D] levels were compared in patients who underwent RYGB from 2002 to 2004. The serum 25(OH)D levels were defined as being optimal (≥80 nmol/L), suboptimal (50–79 nmol/L), or deficient (<50 nmol/L). Patients with deficient 25(OH)D levels were prescribed 50,000 IU ergocalciferol weekly. The remaining patients averaged 710 IU supplemental vitamin D intake daily.ResultsThe mean patient age was 43.8 ± 10.7 years, and the mean preoperative body mass index was 51.8 ± 9.8 kg/m². Of the 95 patients with baseline and 12-month 25(OH)D levels, 89% were women. The mean preoperative 25(OH)D level was 49.7 ± 26.5 nmol/L; 34% had suboptimal 25(OH)D levels and 54% had deficient levels before surgery. Twelve months after surgery, those receiving 50,000 IU weekly (n = 40) had a mean 25(OH)D level of 69.2 ± 22.2 nmol/L; 63% had suboptimal and 8% deficient levels. Those taking 710 IU daily (n = 55) had a mean 25(OH)D level of 85.5 ± 33.0 nmol/L; 44% had suboptimal and 6% deficient levels.ConclusionVitamin D deficiency is prevalent in RYGB patients before surgery. The vitamin D status improved markedly after RYGB surgery with either 710 IU vitamin D daily or 50,000 IU weekly. Current supplementation practices do not appear to optimize the serum 25(OH)D levels and need to be more closely examined.