Prevention of vitamin D deficiency during adolescence:: interventional muticenter study on the biological effects of repeated doses of 100,000 IU of vitamin D3

Recent studies have shown a high prevalence of calcium and vitamin D deficiencies in adolescents. The aim of this present study was to follow the changes in calcium status and 25 hydroxyvitamin D (25[OH]D) and parathyroid hormone (iPTH) levels during winter in preadolescents and adolescents from four university hospitals in northern France. Subjects and methods. - Two groups of teenagers and adolescents (range: 10-15 years) were followed from October 1996 to June 1997 They were given either 100,000 IU of vitamin D (treated group n = 33) or a placebo (control group n = 35) in October January and April. Serum calcium, phosphate, 25(OH)D and iPTH levels were measured at inclusion and every three months thereafter Results. - At inclusion, plasma or serum 25(OH)D levels were less than or equal to 10 ng/mL in 16 subjects and < 6 ng/ mt in six. in control children, no significant change in 25(OH)D occurred during the study while plasma or serum iPTH levels increased to 34 +/- 11 pg/mL. In the treated groups, 25(0H)D levels remained > 20 ng/mL in every subject; no hypercalcemia was observed; and the mean plasma or serum iPTH level was 25 +/- 14 pg/mL at the end of the study. Conclusion, - Teenagers presented with a high prevalence of biological vitamin D deficiency at the end of summer. The increase of iPTH during winter in the unsupplemented group suggests that this has secondary consequences on their calcium homeostasis unless they are supplemented with vitamin D. We advocate a sufficient calcium supply and a 100, 00a IU vitamin D supplement given two or three times during winter to preadolescents and adolescents living in northern France. (C) 2000 Editions scientifiques et medicales Elsevier SAS.