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.     

Efficacy of different doses and time intervals of oral vitamin D supplementation with or without calcium in elderly nursing home residents

Summary The effect of equivalent oral doses of vitamin D3 600 IU/day, 4200 IU/week and 18,000 IU/month on vitamin D status was compared in a randomized clinical trial in nursing home residents. A daily dose was more effective than a weekly dose, and a monthly dose was the least effective. Introduction It is assumed that equivalent daily, weekly or monthly doses of vitamin D3 equally influence vitamin D status. This was investigated in a randomized clinical trial in nursing home residents. Methods The study was performed in ten nursing homes including 338 subjects (76 male and 262 female), with a mean age of 84 (± SD 6.3 years). They received oral vitamin D3 either 600 IU/day, or 4200 IU/week, or 18,000 IU/month or placebo. After 4 months, calcium was added during 2 weeks, 320 mg/day or 640 mg/day or placebo. Outcome: serum levels of 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and bone turnover markers. Statistical approach: linear multilevel analysis. Results At baseline, mean serum 25(OH)D was 25.0 nmol/L (SD 10.9), and in 98%, it was lower than 50 nmol/L. After 4 months, mean serum 25(OH)D levels increased to 62.5 nmol/L (after daily vitamin D3 69.9 nmol/L, weekly 67.2 nmol/L and monthly 53.1 nmol/L, P < 0.001 between groups). Median serum PTH levels decreased by 23% (p < 0.001). Bone turnover markers did not decrease. Calcium supplementation had no effect on serum PTH and bone turnover. Conclusion Daily vitamin D was more effective than weekly, and monthly administration was the least effective.     

High-Dose Vitamin D Supplementation Can Correct Hypovitaminosis D Prior to Total Knee Arthroplasty

BackgroundVitamin D deficiency in the perioperative surgical period is associated with inferior surgical outcomes. There are no established preoperative supplementation regimens in the orthopedic literature. The purpose of this study is to compare the efficacy between 2 different supplementation regimens of vitamin D prior to total knee arthroplasty.MethodsWe conducted a retrospective analysis of 174 patients identified as vitamin D deficient (25(OH)D < 30 ng/mL) who received one of 2 vitamin D supplementation protocols: (1) daily supplementation with D3 on a sliding scale from 1000 to 6000 IU or (2) a loading dose of 50,000 IU D3 weekly for 4 weeks then 2000 IU/d. Serum vitamin D levels were measured at 3 months and 1 month preoperatively.ResultsMean patient age was 65.5(±8.6) years, and 54.6% were female. Deficiency was corrected in 73.3% of patients in the loading dose group and 42.4% of patients in the daily, low-dose group [χ² (1, N = 174) = 16.53, P < .001]. Patients in the loading dose group also achieved a greater average correction in vitamin D levels.ConclusionThis is the first study to compare preoperative vitamin D supplementation protocols. A loading dose regimen of 50,000 IU weekly for 4 weeks followed by a maintenance dose of 2000 IU/d more effectively corrects vitamin D deficiency compared to a low-dose, daily regimen among total knee arthroplasty patients. We recommend this regimen for deficiency correction in patients who have been screened to be deficient in vitamin D preoperatively.     

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.     

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.     

Hip bone loss is attenuated with 1000 IU but not 400 IU daily vitamin D3: A 1‐year double‐blind RCT in postmenopausal women

Few year‐long vitamin D supplementation trials exist that match seasonal changes. The aim of this study was to determine whether daily oral vitamin D₃ at 400 IU or 1000 IU compared with placebo affects annual bone mineral density (BMD) change in postmenopausal women in a 1‐year double‐blind placebo controlled trial in Scotland. White women aged 60 to 70 years (n = 305) were randomized to one of two doses of vitamin D or placebo. All participants started simultaneously in January/February 2009, attending visits at bimonthly intervals with 265 (87%) women attending the final visit and an additional visit 1 month after treatment cessation. BMD (Lunar iDXA) and 1,25‐dihydroxyvitamin D[1,25(OH)₂D], N‐terminal propeptide of type 1 collagen [P1NP], C‐terminal telopeptide of type I collagen [CTX], and fibroblast growth factor‐23 [FGF23] were measured by immunoassay at the start and end of treatment. Circulating PTH, serum Ca, and total 25‐hydroxyvitamin D [25(OH)D] (latter by tandem mass spectrometry) were measured at each visit. Mean BMD loss at the hip was significantly less for the 1000 IU vitamin D group (0.05% ± 1.46%) compared with the 400 IU vitamin D or placebo groups (0.57% ± 1.33% and 0.60% ± 1.67%, respectively) (p < 0.05). Mean (± SD) baseline 25(OH)D was 33.8 ± 14.6 nmol/L; comparative 25(OH)D change for the placebo, 400 IU, and 1000 IU vitamin D groups was ?4.1 ± 11.5 nmol/L, +31.6 ± 19.8 nmol/L, and +42.6 ± 18.9 nmol/L, respectively. Treatment did not change markers of bone metabolism, except for a small reduction in PTH and an increase in serum calcium (latter with 1000 IU dose only). The discordance between the incremental increase in 25(OH)D between the 400 IU and 1000 IU vitamin D and effect on BMD suggests that 25(OH)D may not accurately reflect clinical outcome, nor how much vitamin D is being stored. © 2013 American Society for Bone and Mineral Research.     

Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25‐hydroxyvitamin D

Many patients treated for vitamin D deficiency fail to achieve an adequate serum level of 25‐hydroxyvitamin D [25(OH)D] despite high doses of ergo‐ or cholecalciferol. The objective of this study was to determine whether administration of vitamin D supplement with the largest meal of the day would improve absorption and increase serum levels of 25(OH)D. This was a prospective cohort study in an ambulatory tertiary‐care referral center. Patients seen at the Cleveland Clinic Foundation Bone Clinic for the treatment of vitamin D deficiency who were not responding to treatment make up the stugy group. Subjects were instructed to take their usual vitamin D supplement with the largest meal of the day. The main outcome measure was the serum 259(OH)D level after 2 to 3 months. Seventeen patients were analyzed. The mean age (±SD) and sex (F/M) ratio were 64.5 ± 11.0 years and 13 females and 4 males, respectively. The dose of 25(OH)D ranged from 1000 to 50,000 IU daily. The mean baseline serum 25(OH)D level (±SD) was 30.5 ± 4.7 ng/mL (range 21.6 to 38.8 ng/mL). The mean serum 25(OH)D level after diet modification (±SD) was 47.2 ± 10.9 ng/mL (range 34.7 to 74.0 ng/mL, p < .01). Overall, the average serum 25(OH)D level increased by 56.7% ± 36.7%. A subgroup analysis based on the weekly dose of vitamin D was performed, and a similar trend was observed. Thus it is concluded that taking vitamin D with the largest meal improves absorption and results in about a 50% increase in serum levels of 25(OH)D levels achieved. Similar increases were observed in a wide range of vitamin D doses taken for a variety of medical conditions. © 2010 American Society for Bone and Mineral Research     

High-dose oral vitamin D3 supplementation in rheumatology patients with severe vitamin D3 deficiency

ObjectivesRecent large trials indicate that adherence associated with a daily regimen of vitamin D is low and limits anti-fracture efficacy with vitamin D supplementation. The aim of this report is to describe changes of 25-hydroxyvitamin D (25(OH)D) serum concentrations achieved with a single oral dose of 300 000 IU vitamin D3.MethodsOver a course of 4 months, we identified 33 elderly with severe vitamin D deficiency (25(OH)D < 25 nmol/l) on admission to acute care. Patients were admitted for musculoskeletal pain, bone disease, or gait abnormalities. The mean age was 80.5 years (SD ± 6.1). All patients were treated with a single oral dose of 300 000 IU D3 in combination with 500–1000 mg calcium supplements per day depending on their dietary calcium intake.ResultsBaseline mean 25(OH)D serum concentrations were 15 nmol/l (SD ± 5.5). Mean 25(OH)D serum concentrations increased to 81.4 nmol/l (SD ± 29.7) at 3 months (29 patients) and were still 69.0 nmol/l (SD ± 17.9) at 6 months (26 patients). Mean serum calcium levels were 2.24 mmol/l (SD ± 0.11) at baseline, 2.28 mmol/l (SD ± 0.18) at 3 months, and 2.28 mmol/l (SD ± 0.13) at 6 months. Two patients with mild hypercalcemia (2.69 mmol/l) at 3 months had normal values at 6 months.ConclusionBased on our observations, a single oral dose of 300 000 IU vitamin D3 raises mean 25(OH)D serum concentrations to the target mean of above 75 nmol/l at 3 months and a mean level of 69 nmol/l at 6 months. As calcium absorption is enhanced with higher 25(OH)D serum concentrations, calcium supplementation may need downward adjustment with this regimen to avoid mild hypercalcemia.     

The Efficacy of Vitamin D Supplementation During a Prolonged Submarine Patrol

Submariners spend prolonged periods submerged without sunlight exposure and may benefit from vitamin D supplementation to maintain vitamin D status. The primary objective of this study was to determine the efficacy of daily vitamin D supplementation on maintenance of 25-hydroxyvitamin D (25(OH)D) during a 3-month submarine patrol. Submariners were randomly divided into three groups: placebo (n = 16), 1,000 IU/day (n = 20), or 2,000 IU/day (n = 17). Anthropometrics, self-reported dietary calcium and vitamin D intake, serum markers of vitamin D and bone metabolism, and peripheral quantitative computed tomography (pQCT) parameters of the tibia were determined before and after the patrol. Prior to departure, 49 % of the subjects were vitamin D insufficient (<50 nmol/L). Following the patrol, 25(OH)D increased in all groups (p < 0.001): 3.3 ± 13.1 (placebo), 4.6 ± 11.3 (1,000 IU/day), and 13 ± 14 nmol/L (2,000 IU/day). The changes in 25(OH)D levels were dependent upon the baseline concentration of 25(OH)D and body mass (p < 0.001). Osteocalcin increased by 38 % (p < 0.01), and pQCT analyses revealed small, yet significant increases in indices of tibial structure and strength (p < 0.05) that were independent of supplementation. These data suggest that vitamin D status was low prior to the patrol, and the subsequent changes in vitamin D status were dependent on the baseline 25(OH)D levels and body mass. Furthermore, short-term skeletal health does not appear to be negatively affected by 3 months of submergence in spite of a suboptimal response to vitamin D supplementation.     

High-dose oral vitamin D3 supplementation in the elderly

Summary  Daily dosing with vitamin D often fails to achieve optimal outcomes, and it is uncertain what the target level of 25-hydroxyvitamin D should be. This study found that large loading doses of vitamin D₃ rapidly and safely normalize 25OHD levels, and that monthly dosing is similarly effective after 3–5 months. With baseline 25OHD > 50 nmol/L, vitamin D supplementation does not reduce PTH levels. Introduction  There is concern that vitamin D supplementation doses are frequently inadequate, and that compliance with daily medication is likely to be suboptimal. Methods  This randomized double-blind trial compares responses to three high-dose vitamin D₃ regimens and estimates optimal 25-hydroxyvitamin D (25OHD) levels, from changes in parathyroid hormone (PTH), and procollagen type I amino-terminal propeptide (P1NP) in relation to baseline 25OHD. Sixty-three elderly participants were randomized to three regimens of vitamin D supplementation: a 500,000-IU loading dose; the loading dose plus 50,000 IU/month; or 50,000 IU/month. Results  The Loading and Loading + Monthly groups showed increases in 25OHD of 58 ± 28 nmol/L from baseline to 1 month. Thereafter, levels gradually declined to plateaus of 69 ± 5 nmol/L and 91 ± 4 nmol/l, respectively. In the Monthly group, 25OHD reached a plateau of ~80 ± 20 nmol/L at 3–5 months. There were no changes in serum calcium concentrations. PTH and P1NP were only suppressed by vitamin D treatment in those with baseline 25OHD levels <50 and <30 nmol/L, respectively. Conclusions  Large loading doses of vitamin D₃ rapidly and safely normalize 25OHD levels in the frail elderly. Monthly dosing is similarly effective and safe, but takes 3–5 months for plateau 25OHD levels to be reached.     

Hypovitaminosis D and Bone Mineral Metabolism and Bone Density in Hyperthyroidism

Little is known about the impact of concomitant vitamin D deficiency on bone mineral density in hyperthyroidism. Therefore, we evaluated bone mineral measures in vitamin D–deficient and sufficient patients with hyperthyroidism. Thirty newly diagnosed consecutive patients with hyperthyroidism were included. Blood samples were used for measurement of calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D [25(OH) D], and parathyroid hormone (PTH). Bone mineral density (BMD) was measured at the hip, spine, and forearm. The patients were divided into vitamin D–deficient (<25 nmol/L) and vitamin D–sufficient groups (≥25 nmol/L). Eight (26.6%) patients had 25(OH) D levels less than 25 nmol/L, with mean ± standard deviation (SD) level of 16.5 ± 3.2 (vitamin D–deficient group 1), and the remainder had a mean ± SD of 46.0 ± 13.5 nmol/L (vitamin D–sufficient group 2). Serum-intact PTH levels were significantly higher in group 1 compared with those in group 2 (31.2 ± 16.3 vs 18.0 ± 13.1 pg/mL; p = 0.041). In the vitamin D–deficient group, the mean BMD T-scores were in the osteoporotic range at hip and forearm (?2.65 ± 1.13 and ?3.04 ± 1.3) and in the osteopenia range at lumbar spine (?1.83 ± 1.71). However, in vitamin D–sufficient group, the mean BMD T-scores were in the osteopenia range (?1.64 ± 1.0, ?1.27 ± 1.6, and ?1.60 ± 0.7) at hip, forearm, and lumbar spine, respectively. The mean BMD Z-scores were also significantly lower in vitamin D–deficient group compared with those in vitamin D–sufficient group. Finally, BMD values (gm/cm²) at the hip and forearm were significantly lower in the vitamin D–deficient group compared with those in the vitamin D–sufficient group. In conclusion, hyperthyroid patients with concomitant vitamin D deficiency had lower BMD compared with vitamin D–sufficient patients.     

Unusually prolonged vitamin D intoxication after discontinuation of vitamin D: possible role of primary hyperparathyroidism

A 77-year-old woman had taken 50,000 IU of vitamin D2 daily, instead of once weekly, for over 2 years. She developed severe hypercalcemia, and after stopping vitamin D, her serum 25-hydroxyvitamin D (25(OH)D) remained higher than 250 nmol/l for almost 2(1/2) years. Inappropriately high parathyroid (PTH) concentrations were particularly evident after serum calcium was suppressed to slightly above the reference range by the administration of intravenous pamidronate and prednisone. It seems that an underlying primary hyperparathyroidism that was masked initially by the hypercalcemia of vitamin D intoxication was responsible for the unusually prolonged half-life of 25(OH)D in the blood. After vitamin D2 had been stopped, the decline in serum 25(OH)D was unusually slow. In this unusual case, primary hyperparathyroidism probably prevented an appropriate increase in the vitamin D-catabolizing enzyme, 25(OH)D-24-hydroxylase, thereby slowing metabolic clearance of 25(OH) vitamin D.     

High Prevalence of Vitamin D Insufficiency in Southern Chinese Renal Transplant Recipients

Vitamin D deficiency is common globally. There is evidence that vitamin D status may be related to immune function and cardiovascular disease. The vitamin D status of Chinese kidney transplant recipients has never been investigated. We performed a cross-sectional study and measured the level of 25-hydroxyvitamin D [25(OH)D] in 94 Chinese renal transplant recipients with stable allograft function. Vitamin D deficiency and insufficiency were detected in 43.6% and 54.2% of patients, respectively. About 53.2% of the patients also had elevated parathyroid hormone (PTH) levels. The level of 25(OH)D was lower in kidney transplant recipients compared with healthy controls matched for age and sex (52.5 ± 15.6 nmol/L vs. 57.5 ± 19.0 nmol/L, p = 0.05), but the level of serum creatinine was higher in kidney transplant recipients (120.3 ± 48.5 μmol/L and 78.3 ± 15.3 μmol/L, p < 0.01). The level of 25(OH)D was negatively correlated with that of PTH (p = 0.001). The latter was associated with serum creatinine (p = 0.001) and duration of dialysis (p = 0.001). Patients with a history of acute rejection showed lower levels of 25(OH)D (45.3 ± 11.9 nmol/L vs. 54.2 ± 16.0 nmol/L, p = 0.003). We conclude that vitamin D deficiency is prevalent among Chinese renal transplant recipients. In view of the potential immunomodulatory effect of vitamin D, the relationship between vitamin D level and rejection and the effect of vitamin D supplementation in renal transplant recipients warrant further investigations.     

Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25‐hydroxyvitamin D response to supplementation

It is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts of dietary fat on vitamin D absorption is not established. This study was conducted to determine whether the presence of a meal and the fat content of the meal influences vitamin D absorption or the 25‐hydroxyvitamin D [25(OH)D] response to supplemental vitamin D₃. Based on earlier studies in rats we postulated that absorption would be greatest in the low‐fat meal group. Sixty‐two healthy older men and women were randomly assigned to one of three meal groups: no meal, high‐fat meal, or low‐fat meal; each was given a monthly 50,000 IU vitamin D₃ supplement with the test breakfast meal (or after a fast for the no‐meal group) and followed for 90 days. Plasma vitamin D₃ was measured by liquid chromatography–mass spectroscopy (LC/MS) before and 12 hours after the first dose; plasma 25(OH)D was measured by radioimmunoassay at baseline and after 30 and 90 days. The mean 12‐hour increments in vitamin D₃, after adjusting for age and sex, were 200.9 nmol/L in the no‐meal group, 207.4 nmol/L in the high‐fat meal group, and 241.1 nmol/L in the low‐fat meal group (p = 0.038), with the increase in the low‐fat group being significantly greater than the increases in the other two groups. However, increments in 25(OH)D levels at 30 and 90 days did not differ significantly in the three groups. We conclude that absorption was increased when a 50,000 IU dose of vitamin D was taken with a low‐fat meal, compared with a high‐fat meal and no meal, but that the greater absorption did not result in higher plasma 25(OH)D levels in the low‐fat meal group.     

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.     

Finding the Optimal Dose of Vitamin D Following Roux-en-Y Gastric Bypass: A Prospective, Randomized Pilot Clinical Trial

Background  Vitamin D deficiency is common following bariatric surgery and is due to a combination of baseline deficiency and postoperative malabsorption. There are few prospective studies evaluating the appropriate dose of vitamin D to prevent and treat vitamin D deficiency following bariatric surgery. Methods  We evaluated three doses of vitamin D3 (800, 2,000, and 5,000 IU/day) in a prospective, randomized pilot trial of 45 patients undergoing Roux-en-Y gastric bypass. Serum 25 hydroxy Vitamin D (25OHD), intact PTH (iPTH), calcium, and urine calcium/creatinine ratios were measured at 6, 12, and 24 months postoperatively. Due to a high dropout rate at 24 months, we focus on the 12-month data. Results  At 12 months, the 800-, 2,000-, and 5,000-IU groups had a mean ± SD increase in 25OHD of 27.5 ± 40.0, 60.2 ± 37.4, and 66.1 ± 42.2 nmol/L, respectively (p = 0.09) with a maximum increase in each group of 87.4, 114.8, and 129.8 nmol/L. Forty-four percent, 78%, and 70% achieved 25OHD levels ≥75 nmol/L (p = 0.38). Results for the 6- and 24-month time points were similar to the 12-month results. Mean weight loss at 24 months of the study was not different among groups (p = 0.52). Serum calcium did not change significantly, and there were no cases of hypercalcemia or sustained hypercalciuria. Conclusions  Higher doses of vitamin D supplementation trend towards higher levels of 25OHD. Vitamin D replacement as high as 5,000 IU /day is safe and necessary in many patients to treat vitamin D deficiency following Roux-en-Y gastric bypass yet is still suboptimal in others.     

Vitamin D3 Dose Requirement to Raise 25‐Hydroxyvitamin D to Desirable Levels in Adolescents: Results from a Randomized Controlled Trial

Several organizations issued recommendations on desirable serum 25‐hydroxy vitamin D [25(OH)D] levels and doses of vitamin D needed to achieve them. Trials allowing the formulation of evidence‐based recommendations in adolescents are scarce. We investigated the ability of two doses of vitamin D₃ in achieving recommended vitamin D levels in this age group. Post hoc analyses on data from a 1‐year double‐blind trial that randomized 336 Lebanese adolescents, aged 13 ± 2 years, to placebo, vitamin D₃ at 200 IU/day (low dose), or 2000 IU/day (high dose). Serum 25(OH)D level and proportions of children achieving levels ≥20 ng/mL and 30 ng/mL were determined. At baseline, mean 25(OH)D was 15 ± 7 ng/mL, 16.4 ± 7 ng/mL in boys, and 14 ± 8 ng/mL in girls, p = 0.003, with a level ≥20 ng/mL in 18% and ≥30 ng/mL in 5% of subjects. At 1 year, mean levels were 18.6 ± 6.6 ng/mL in the low‐dose group, 17.1 ± 6 ng/mL in girls, and 20.2 ± 7 ng/mL in boys, p = 0.01, and 36.3 ± 22.3 ng/mL in the high‐dose group, with no sex differences. 25(OH)D increased to ≥20 ng/mL in 34% of children in the low‐dose and 96% in the high‐dose group, being higher in boys in the low‐dose arm only; it remained ≥30 ng/mL in 4% of children in the low‐dose arm but increased to 64% in the high‐dose arm. Baseline 25(OH)D level, body mass index (BMI), and vitamin D dose assigned were the most significant predictors for reaching a 25(OH)D level ≥20 ng/mL and 30 ng/mL. A daily dose of 2000 IU raised 25(OH)D level ≥20 ng/mL in 96% of adolescents (98% boys versus 93% girls). Dose‐response studies are needed to determine in a definitive manner the daily allowance of vitamin D for Middle Eastern adolescents with a similar profile. © 2014 American Society for Bone and Mineral Research.     

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status

Roux‐en‐Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)₂D‐mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m²). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6‐month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24‐hour urinary Ca decreased, PTH increased, and 1,25(OH)₂D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = ?0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long‐term skeletal consequences should be investigated. © 2015 American Society for Bone and Mineral Research.     

25-Hydroxyvitamin D in Canadian adults: biological, environmental, and behavioral correlates

Summary

We assessed vitamin D status and its correlates in the population-based Canadian Multicentre Osteoporosis Study (CaMos). Results showed that serum 25-hydroxyvitamin D levels <75?nmol/L were common. Given Canada??s high latitude, attention should be given to strategies for enhancing vitamin D status in the population.

Introduction

Inadequate vitamin D has been implicated as a risk factor for several clinical disorders. We assessed, in a Canadian cohort, vitamin D status and its correlates, based on serum 25-hydroxyvitamin D [25(OH)D], the best functional indicator of vitamin D status.

Methods

We studied 577 men and 1,335 women 35+ years from seven cities across Canada in the randomly selected, population-based Canadian Multicentre Osteoporosis Study (CaMos). Participants completed a comprehensive questionnaire. Serum 25(OH)D was measured by immunoassay. Multivariate linear regression modeling assessed the association between 25(OH)D and determinants of vitamin D status.

Results

Participants (2.3%) were deficient in 25(OH)D (<27.5?nmol/L); a further 18.1% exhibited 25(OH)D insufficiency (27.5?C50?nmol/L). Levels <75?nmol/L were evident in 57.5% of men and 60.7% of women and rose to 73.5% in spring (men) and 77.5% in winter (women); 25(OH)D <50?nmol/L was ??10% year round for those supplementing with ??400?IU vitamin D/day but was 43.9% among those not supplementing in winter and spring. The strongest predictors of reduced 25(OH)D for both men and women were winter and spring season, BMI ??30, non-white ethnicity, and lower vitamin D supplementation and its modification by fall and winter.

Conclusions

In this national Canadian cohort, vitamin D levels <75?nmol/L were common, particularly among non-white and obese individuals, and in winter and spring. Vitamin D intake through diet and supplementation and maintenance of normal weight are key modifiable factors for enhancing vitamin D status and thus potentially influencing susceptibility to common chronic diseases.