No Severe Hypercalcemia with Daily Vitamin D3 Supplementation of up to 30 μg during the First Year of Life

Abstract

Vitamin D supplementation is widely recommended for infants, but the optimal dose remains unclear. High intake may result in hypercalcemia. Methods: We evaluated the incidence of hypercalcemia during the first year of life in a cohort of 987 healthy children who received 10 or 30 μg of vitamin D3 supplementation daily. Ionized calcium (Caion) was analyzed at 6 and 12 months, and serum 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH) concentration at 12 months. Severe hypercalcemia was defined as Ca-ion exceeding the reference limit (1.16-1.39 mmol/L) by 10%. Results: No severe hypercalcemia occurred. Mild hypercalcemia (1.40-1.52 mmol/L) was present at 6 months in 28% and at 12 months in 2% of infants. At 12 months, 25-OHD ranged between 23 and 241 nmol/L (median 97), and PTH was between undetectable and 104 pg/mL (median 24) and was below the reference range (11.5-78.4 pg/mL) in 11%. 25-OHD and Ca-ion correlated positively (r = 0.149), and 25-OHD was slightly higher in the 12 infants with mild hypercalcemia (median 97 vs. 110 nmol/L, p = 0.046). Conclusions: Vitamin D3 supplementation of 10 or 30 μg did not cause severe hypercalcemia. Mild hypercalcemia was more prevalent at 6 months than at 12 months, and was associated weakly with 25-OHD at 12 months.