VITAMIN-D AND PUBERTAL MATURATION - INTEREST AND TOLERANCE OF VITAMIN-D SUPPLEMENTATION DURING THE WINTER

Background. - In France, several cases of vitamin D-deficiency rickets among adolescents have been reported, but no prophylaxis measure has been systematically recommended at this age. The aim of this study was to measure 25-hydroxyvitamin D (25-(OH)D) levels and to search for biological signs of vitamin D deficiency during adolescence. Moreover, the effects of a unique oral dose of 100 000 IU of vitamin D3, given during the winter, were analysed. Population and methods. - Circulating levels of 25-(OH)D, 1,25-dihydroxyvitamin D, intact parathyroid hormone (iPTH), alkaline phosphatase activities, calcium and phosphate were measured in 53 adolescents aged 10-17 years (81% of metropolitan origin), seen during the winter. The effect of a single oral dose of 100 000 IU of vitamin D3 or of placebo was studied in 15 of these subjects. Results. - 24,5% of the adolescents had low 25-(OH)D concentrations (< 6 ng/ml), this frequency being even more elevated (38%) at the end of pubertal maturation (stages 4 and 5). An increase in iPTH concentrations was found in subjects with lowest 25-(OH)D levels (< 3 ng/ml). An oral dose of 100 000 IU of vitamin D3 resulted in a significant increase in the 25-(OH)D levels; yet, these levels remained within the normal range during the 1-2 month follow-up of the nine treated subjects. This dosage made it possible to correct the low calcium concentrations (2.20-2.24 mmol/l) found before treatment in three adolescents. Conclusions. - The high frequency of low vitamin D status observed during puberty and its normalization after a 100 000 IU vitamin D3 supplementation show the interest and safety of this intermittent 100 000 IU vitamin D3 supplementation to adolescents during the winter season.