• Nineteen preterm infants born at or before 32 weeks of gestation were studied to determine the dose of calcitriol that would be effective in the prophylaxis of early neonatal hypocalcemia (serum calcium level, <7.0 mg/dL [<1.75 mmol/L]). In these infants the course of early neonatal hypocalcemia was not modified by calcitriol administration. Serum 1,25-dihydroxyvitamin D level rose in response to intramuscular administration of calcitriol. The incidence of hypocalcemia in these infants was 37% by 12 hours, 83% by 24 hours, and 89% by 36 hours. Thus, in extremely preterm infants, the incidence of early neonatal hypocalcemia is higher and the onset earlier than in larger preterm infants; furthermore, in these infants the hypocalcemia is refractory even to high doses of calcitriol.
Venkataraman PS, Tsang RC, Steichen JJ, Grey I, Neylan M, Fleischman AR. Early Neonatal Hypocalcemia in Extremely Preterm InfantsHigh Incidence, Early Onset, and Refractoriness to Supraphysiologic Doses of Calcitriol. Am J Dis Child. 1986;140(10):1004–1008. doi:10.1001/archpedi.1986.02140240050025