Hypocalcemia is a total serum calcium concentration < 8 mg/dL (< 2 mmol/L) in term infants or < 7 mg/dL (< 1.75 mmol/L) in preterm infants. It is also defined as an ionized calcium level < 3.0 to 4.4 mg/dL (< 0.75 to 1.10 mmol/L), depending on the method (type of electrode) used. Signs are primarily neurologic and include hypotonia, apnea, and tetany. Treatment is IV or oral calcium supplementation.
(See also general discussion of hypocalcemia.)
Etiology of Neonatal Hypocalcemia
Neonatal hypocalcemia occurs in 2 forms:
Early onset (in the first 2 days of life)
Late onset (> 3 days), which is rare
Some infants with congenital hypoparathyroidism (eg, caused by DiGeorge syndrome) with agenesis or dysgenesis of the parathyroid glands have both early and late (prolonged) hypocalcemia.
Early-onset hypocalcemia
Risk factors for early-onset hypocalcemia include prematurity, being small for gestational age, maternal diabetespreterm neonates
Late-onset hypocalcemia
The cause of late-onset hypocalcemia is usually ingestion of cow’s milk or formula with a too-high phosphate load; elevated serum phosphate leads to hypocalcemia.
Symptoms and Signs of Neonatal Hypocalcemia
Symptoms and signs of neonatal hypocalcemia rarely occur unless total serum calcium is < 7 mg/dL (< 1.75 mmol/L) or the ionized calcium is < 3.0 mg/dL (< 0.75 mmol/L). Signs include hypotonia, tachycardia, tachypnea, apnea, poor feeding, jitteriness, tetany, and seizures. Similar symptoms may occur with hypoglycemia and opioid withdrawal.
Diagnosis of Neonatal Hypocalcemia
Total or ionized serum calcium level
Diagnosis of neonatal hypocalcemia is by measurement of total or ionized serum calcium; ionized calcium is the more physiologic measurement, because it does not require correction for protein concentration and pH. Prolongation of the corrected QT interval (QTc) on ECG also suggests hypocalcemia.
Treatment of Neonatal Hypocalcemia
Early-onset hypocalcemia ordinarily resolves in a few days, and asymptomatic neonates with serum calcium levels > 7 mg/dL (1.75 mmol/L) or ionized calcium > 3.5 mg/dL (0.88 mmol/L) rarely require treatment. Those term infants with levels < 7 mg/dL (1.75 mmol/L) and preterm infants with calcium < 6 mg/dL (<
Late-onset hypocalcemia
Key Points
Neonatal hypocalcemia usually occurs within the first 2 days of life and is most often caused by prematurity, being small for gestational age, maternal diabetes or hyperparathyroidism, and perinatal asphyxia.
Neonates may have hypotonia, tachycardia, tachypnea, apnea, poor feeding, jitteriness, tetany, and/or seizures.
Diagnose by measuring total or ionized serum calcium level; measure glucose level to rule out hypoglycemia.
