PE19.11 | Neonatal Hypocalcemia — Summary & Reflection

KEY TAKEAWAYS

Neonatal hypocalcemia (total Ca <7.5 mg/dL term / <7.0 mg/dL preterm, or ionised Ca <1.0 mmol/L) is classified as early-onset (<72 hours: prematurity, IDM, asphyxia — low PTH) or late-onset (>72 hours: high-phosphate cow's milk, vitamin D deficiency, hypomagnesaemia, DiGeorge syndrome). Clinical features range from asymptomatic to jitteriness, apnoea, seizures, and laryngospasm; QTc prolongation is the key ECG sign. Treatment of symptomatic cases requires IV calcium gluconate 10% at 1–2 mL/kg over 10–30 minutes with mandatory continuous cardiac monitoring. Hypomagnesaemia must be corrected (MgSO₄ 50%, 0.2 mL/kg IM) before calcium therapy will succeed. Mild asymptomatic cases respond to oral calcium supplementation and treatment of the underlying cause.

REFLECT

The infant in the hook was fed undiluted cow's milk formula, developed late-onset hypocalcemia from phosphate overload, and presented with Chvostek's sign. Before you treat, you must check serum magnesium — treating the calcium without correcting a co-existing hypomagnesaemia will fail. Reflect on how this single case integrates physiology (PTH-magnesium dependency), biochemistry (phosphate-calcium interaction), pharmacology (calcium gluconate cardiac risk), and clinical examination (Chvostek's sign, QTc). How does this contrast with an early-onset case in a preterm IDM? What would change in your management approach?