[Vitamin D in childhood].
Infantile Nutritional Rickets has disappeared almost completely in France since 1992 as vitamin D enriched formula availability and previous vitamin D supplementation of infants. The search of evocative symptoms of rickets should be a routine procedure in infants, in particular in case of insufficient vitamin D intake i.e. breastfeeding, and the possibility of vitamin D resistant rickets. Hypocalcaemia occurs not only at the first but also the advanced stages of vitamin D deficiency, and may be responsible for severe cardiologic, neurologic or respiratory complications with possibility of infant death. For the young children between 1 and 5 years and for adolescents, vitamin D insufficiency is responsible for poor skeletal mineralization, loss of bone strength, and a reduction of peak of bone mineral mass at the end of puberty. The new Dietary Reference Intakes (DRI, 2011) increased greatly the Recommended Dietary allowances (RDA) from 200 to 600 IU/d (15 μg/d) for individuals from 1 to 70 years of age. These levels are not reached in winter, even in countries, like USA and Canada, where vitamin D milk fortification is mandatory and others like Japan and North-European countries despite high fish consumption. From 1 to 5 years of age and during adolescence, a winter vitamin D3 supplementation is necessary with 80.000 or 100.000 IU periodic loads every 3 months i.e. in November and February. In cases of an underlying risk, i.e. insufficient vitamin D photosynthesis in summertime (dark skin, wearing heavily skin-covering clothes, or several skin diseases), or digestive, renal or nutritional pathologies, use of some drugs, loading dose of 80.000 or 100.000 IU, every 3 months should be administered over the year.