E. M. Stein*, G. Strain†, N. Sinha‡, D. Ortiz‡, A. Pomp†, G. Dakin†, D. J. McMahon*, R. Bockman‡§ and S. J. Silverberg*
*Division of Endocrinology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York , †Department of Surgery, Weill Cornell Medical College, New York , ‡Division of Endocrinology, Department of Medicine, Weill Cornell Medical College, New York and §Division of Endocrinology, Department of Medicine, Hospital for Special Surgery, New York, NY, USA
Correspondence: Shonni J. Silverberg, 630 West 168th Street, PH8 West – 864, New York, NY 10032, USA. Tel.: +1 212 305 6238; Fax: +1 212 305 6486; E-mail: sjs5 at columbia.edu Copyright © 2009 Blackwell Publishing Ltd
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/m2 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 = ?0·36, P < 0·01). Each BMI increase of 1 kg/m2 was associated with a 1·3 nmol/l decrease in 25OHD (P < 0·01). BMI, sun exposure, African American race and PTH predicted 40% of the variance in 25OHD (P < 0·0001). Serum 25OHD significantly increased at 4 and 8 weeks in both treatment groups (P < 0·001), whereas PTH(1-84) declined significantly in subjects treated with cholecalciferol (P < 0·007) and tended to decrease following ergocalciferol (P < 0·09).
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.