Transient neonatal hypocalcemia: presentation and outcomes.

OBJECTIVE: To determine the incidence of moderate-to-severe transient neonatal hypocalcemia in term neonates and to describe the characteristics of affected infants and the outcomes of their management.

METHODS: We reviewed medical records of all term infants <31 days of age who presented to Children's Medical Center Dallas from 2001 to 2009 with hypocalcemia (ionized calcium <1.00 mmol/L [4.00 mg/dL]).

RESULTS: Seventy-eight infants met criteria. Median (interquartile range) age at admission was 8.0 (7.0-10.0) days, and median duration of admission was 3.0 (2.0-4.0) days. Most infants were male (71.8%) and Hispanic (62.8%). Neonates were generally severely hypocalcemic and hyperphosphatemic. Seventy-five of 78 were hypomagnesemic, and the majority had low or inappropriately normal parathyroid hormone responses. Levels of 25-hydroxyvitamin D were ≤ 62.4 nmol/L (25 ng/mL) in all 42 infants in whom they were determined. All infants responded to therapy of limited duration with 1 or more of the following: calcium supplements, calcitriol, low phosphorus formula, and magnesium supplementation. Neuroimaging did not affect management decisions in any neonate.

CONCLUSIONS: Moderate-to-severe late-onset neonatal hypocalcemia is more common in Hispanic and male infants, is often a sign of coexistent vitamin D insufficiency or deficiency and hypomagnesemia, and is readily managed with therapy of limited duration. Neonates presenting with seizures who are found to be hypocalcemic are unlikely to benefit from neuroimaging evaluations.