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Plasma 25-hydroxyvitamin D and rickets in infants of extremely low birthweight
Insights
Rickets affects extremely low birthweight infants even with high vitamin D. High vitamin D levels and spontaneous healing suggest supplementation isn
Area of Science:
- Neonatology
- Pediatric Endocrinology
- Nutritional Science
Background:
- Rickets is a recognized complication in extremely low birthweight (ELBW) infants.
- High doses of ergocalciferol supplementation (2000 units/day) were administered to ELBW infants in 1981.
- Despite supplementation, a significant number of ELBW infants developed rickets.
Purpose of the Study:
- To investigate the cause of rickets in ELBW infants.
- To determine if current vitamin D supplementation protocols are adequate for ELBW infants.
- To explore potential alternative causes or contributing factors to rickets in this population.
Main Methods:
- Observational study of 15 neonatal survivors with birthweight < 1000 g over a 1-year period.
- Radiological diagnosis of rickets.
- Measurement of plasma 25-hydroxyvitamin D concentrations.
- Assessment of treatment response to ergocalciferol and alfacalcidol, and spontaneous healing.
Main Results:
- 8 out of 15 ELBW infants developed rickets at a mean postnatal age of 8 weeks.
- All affected infants had normal or high plasma 25-hydroxyvitamin D levels (mean 80 nmol/l).
- Rickets healed spontaneously in 4 infants and with alfacalcidol in another 4, despite continued ergocalciferol in some.
Conclusions:
- Inadequate vitamin D supplementation is unlikely to be the primary cause of rickets in ELBW infants.
- The high prevalence of rickets despite adequate vitamin D levels suggests other etiological factors.
- Further research is needed to understand the pathogenesis of rickets in ELBW infants.
Abstract:
Rickets is now a well-known entity in infants of very low birthweight. In a 1-year period (1981) 8 of 15 neonatal survivors whose birthweight was less than 1000 g (extremely low birthweight) developed rickets despite high supplementation with ergo-calciferol, 2000 units a day. At the time of radiological diagnosis their postnatal age was 8 (range 5-14) weeks, and they all had normal or high plasma concentrations of 25-hydroxyvitamin D (mean 80 nmol/l, range 40-160 nmol/l). Although 4 infants received alfacalcidol which healed the rickets, in 4 infants the rickets healed spontaneously without change in treatment. The results suggest that inadequate vitamin D supplementation is not the cause of rickets in such infants.