Elevated serum calcium and osteocalcin levels from calcitriol in preterm infants. A prospective randomized study
W. W. Koo, R. C. Tsang, J. W. Poser, P. Laskarzewski, D. Buckley, R. Johnson and J. J. Steichen
The hypothesis of this study was that pharmacologic doses of calcitriol
(1,25-dihydroxyvitamin D3) would result in elevated levels of serum
osteocalcin, the major noncollagenous bone protein, and calcium in infants
of very low birth weight (less than 1500 g). Twenty-four infants of very
low birth weight but of the appropriate weight for gestational age were
matched in 250-g weight ranges and randomized into calcitriol treatment and
control groups on the first day after birth. Treated infants received 4
micrograms/kg of calcitriol intravenously on entry and on the second and
third study days. Controls did not receive calcitriol. Four infants from
each group were hypocalcemic (serum calcium level, less than 7.0 mg/dL
[less than 1.75 mmol/L]) on entry (five to 20 hours after birth) to the
study. Seven infants received calcium replacement; data analyses with and
without these infants were similar. Of the remaining 17 infants, eight were
in the treatment group and nine were in the control group. Calcitriol
significantly increased serum calcium and osteocalcin concentrations on
days 2, 3, and 4 after birth compared with the control group. None of eight
treated infants manifested hypocalcemia after calcitriol vs eight of nine
controls. There were no acute changes in heart rate, respiratory rate,
systolic blood pressure, or urinary calcium loss nor were there changes at
the infusion site, but the diastolic blood pressure increased with
treatment. Although high doses of calcitriol may elevate serum calcium
concentrations in infants of very low birth weight, we suggest that the
long-term or subtle biologic effects of high doses of calcitriol remain to
be studied and that its routine use not be recommended at present.