Vitamin D &/or calcium deficiency rickets in infants & children: a global perspective.

It was only in the early part of the 20th century with the discovery of vitamin D and of the role that ultraviolet light irradiation plays in vitamin D formation that rational and appropriate therapy became available and rickets was all but eradicated in a number of developed countries. Since then, there has been a resurgence of the disease in many countries such as in Europe and the USA probably due to an increase in the prevalence of breast feeding, the immigration of dark skinned families to countries of high latitude, and the avoidance of direct sunlight because of the risk of the development of skin cancers. The disease is also widely recognised in many developing countries, including some situated in subtropical regions. Studies have led to the realization that nutritional rickets may be caused by either vitamin D or calcium deficiency, but in the majority of situations variable combinations of both probably play a role. Although low dietary calcium intakes appear to be central to the pathogenesis of rickets in Nigeria, genetic and/or other environmental factors are likely to contribute. But to date no single factor has been isolated as contributing significantly. The results of a recently conducted study suggest that in situation of low dietary calcium intakes vitamin D requirements may be higher than normal, possibly predisposing those children with vitamin D levels in the low normal range to rickets. If this is so, it would indicate that the currently accepted normal range for vitamin D sufficiency would need to be adjusted depending on dietary calcium intakes. Yet we are still unclear as to the factors which predispose some children to the disease.