Vitamin D insufficiency: evaluation of an oral standardized supplementation using 100,000 IU vials of cholecalciferol, depending on initial serum level of 25OH vitamin D.

Objectives: There is no protocol of vitamin D supplementation used worldwide due to a great disparity of vitamin D supplements available in different countries. The aim of this study was to evaluate the efficiency of the protocol most often used in France to correct vitamin D deficiency defined by a serum 25-hydroxy vitamin D (25OHD) level of less than 30 ng/mL.

Methods: This was a pragmatic multicentric study of vitamin D supplementation in 257 osteopenic/osteoporotic, vitamin D deficient patients who received 100,000 UI vitamin D3 vials every two weeks according to their initial serum 25OHD level (four vials when 25OHD less than 10 ng/mL, three when 25OHD was 10-19 ng/mL, two when 25OHD was 20-29 ng/mL). Blood samples were obtained at baseline, one (M1), two (M2), and three months (M3), after the end of the supplementation protocol.

Results: At M1, 198/257 (77%) patients had a serum 25OHD level more than 30 ng/mL. Eighty-five percent of those with a BMI less than 25 kg/m2 had a 25OHD concentration more than 30 ng/mL, whereas only 66% of those with a BMI more than 25 had a level more than 30 ng/mL. At M2 and M3, 25OHD levels decreased significantly with 55% and 46% having still a level more than 30 ng/mL respectively, without any significant difference according to the initial 25OHD level.

Conclusion: This protocol was effective in rising serum 25OHD of most vitamin D insufficient patients with a BMI less than 25 kg/m2, but not in overweight patients. As almost one half of our patients had a serum 25OHD level less than 30 ng/mL at M2, we suggest that regular doses should be started quite soon after this initial supplementation.