Prevention of vitamin D deficiency during adolescence: interventional muticenter study on the biological effects of repeated doses of 100,000 IU of vitamin D-3

Recent studies have shown a high prevalence of calcium and vitamin D defici encies in adolescents. The aim of this present study was to follow the chan ges in calcium status and 25 hydroxyvitamin D (25[OH]D) and parathyroid hor mone (iPTH) levels during winter in preadolescents and adolescents from fou r 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 eith er 100,000 IU of vitamin D (treated group n = 33) or a placebo (control gro up n = 35) in October January and April. Serum calcium, phosphate, 25(OH)D and iPTH levels were measured at inclusion and every three months thereafte r Results. - At inclusion, plasma or serum 25(OH)D levels were less than or e qual 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 obse rved; and the mean plasma or serum iPTH level was 25 +/- 14 pg/mL at the en d of the study. Conclusion, - Teenagers presented with a high prevalence of biological vita min D deficiency at the end of summer. The increase of iPTH during winter i n 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 l iving in northern France. (C) 2000 Editions scientifiques et medicales Else vier SAS.