Protean manifestations of vitamin D deficiency, part 1: the epidemic of deficiency.

Just when vitamin deficiencies were thought to be a "thing of the past" a new vitamin deficiency-that of vitamin D has developed over the past 20 years. Vitamin D works like a hormone being produced primarily in one organ (the kidney) before circulating through the bloodstream to multiple organs where it has multiple effects. The increased prevalence of vitamin D deficiency is due to changes in modern lifestyle-mainly lack of exposure to sunlight and the increased prevalence of obesity that, results in sequestration of this fat-soluble vitamin in adipose tissue. Distance from the Equator and increasing age and skin pigmentation are additional risk factors. In pregnancy vitamin D deficiency can result in low birth weight, pre-term labor, pre-term birth, infections, and pre-eclamptic toxemia. While vitamin D deficiency is classically associated with rickets and osteomalacia, its effects are much more protean.