Plasma 25-hydroxyvitamin D and rickets in infants of extremely low birthweight.

Abstract

Rickets in now a well known entity in infants of very low birthweight. In a 1 yr period (1981) 8 of 15 neonatal survivors whose birthweight was < 1000 g (extremely low birthweight) developed rickets despite high supplementation with ergo-calciferol, 2000 U/day. At the time of radiological diagnosis their postnatal age was 8 (range 5-14) wk and they all had normal or high plasma concentrations of 25-hydroxyvitamin D (mean 80 nmol/1, range 40-160 nmol/1). Although 4 infants received alfacalcidol which healed the rickets, in 4 infants the rickets healed spontaneously without change in treatment. Inadequate vitamin D supplementation is not the cause of rickets in such infants.