Vitamin D insufficiency prior to bariatric surgery: risk factors and a pilot treatment study

P>Objective To assess vitamin D status and the influences of race, sun exposure and dietary vitamin D intake on vitamin D levels, and to evaluate two vitamin D repletion regimens in extremely obese patients awaiting bariatric surgery. Methods A cross-sectional analysis of dietary vitamin D, sun exposure, PTH [intact (iPTH) and PTH(1-84)] and 25-hydroxyvitamin D (25OHD; differentiated 25OHD2 and 25OHD3) in 56 obese [body mass index (BMI) > 35 kg/m(2)] men and women (age 20-64 years). In a pilot clinical trial, 27 subjects with 25OHD levels < 62 nmol/l were randomized to receive ergocalciferol or cholecalciferol for 8 weeks. Results Serum 25OHD was low (mean 45 +/- 22 nmol/l) and was inversely associated with BMI (r = -0 center dot 36, P < 0 center dot 01). Each BMI increase of 1 kg/m(2) was associated with a 1 center dot 3 nmol/l decrease in 25OHD (P < 0 center dot 01). BMI, sun exposure, African American race and PTH predicted 40% of the variance in 25OHD (P < 0 center dot 0001). Serum 25OHD significantly increased at 4 and 8 weeks in both treatment groups (P < 0 center dot 001), whereas PTH(1-84) declined significantly in subjects treated with cholecalciferol (P < 0 center dot 007) and tended to decrease following ergocalciferol (P < 0 center dot 09). Conclusions In severely obese individuals, those who are African American, have higher BMI and limited sunlight exposure are at greatest risk for vitamin D insufficiency. These demographic factors can help to identify at-risk patients who require vitamin D repletion prior to bariatric surgery. Commonly prescribed doses of ergocalciferol and cholecalciferol are effective in raising 25OHD. Further investigation is needed to evaluate whether these regimens have differential effects on PTH, and to determine the optimal regimen for vitamin D repletion in the extremely obese patient.