[Convulsions and neonatal hypoparathyroidism revealing maternal hyperparathyroidism]

Severe prolonged hypocalcemia may occur in neonates whose parathyroid hormone production has been blocked by maternal hyperparathyroidism. This report describes such a case.

A 7 day-old girl was admitted suffering from dyspnea and repeated convulsions that had continued for 2 days. Her birthweight was 3,500 g and her height 50 cm. Her mother had been given an iron preparation and calcium during pregnancy. Clinical examination of the newborn at birth revealed a cleft palate and micrognathia. The baby had been given milk-formula plus ergocalciferol, 1,200 IU/day. At admission, the baby was hypotonic. Her serum total calcium was 1.27 mmol/l; total proteins 61 g/l; ionized calcium 1.1 mmol/l; phosphorus 2.14 mmol/l; intact PTH 21 pg/ml (N = 10-65) and 25(OH)D 8 ng/ml (N = 8-30). She was given intravenous calcium gluconate (1 g/m2/d), diazepam (0.5 mg/kg) rectally, intravenous phenobarbital (20 mg/kg) but intravenous phenytoin was needed to stop clinical and electrical seizures. Her blood calcium was normalized 5 days later. Her mother, who was clinically normal, had: total serum calcium: 2.72 and 2.77 mmol/l; total proteins: 71 g/l; phosphorus: 0.85 mmol/l; intact PTH: 73 pg/ml; 25(OH)D: 6 ng/ml; Ultrasonography showed an adenoma of the right parathyroid. Further studies on the baby showed no signs of Di George syndrome.

Neonatal hypocalcemia always requires investigation of both the infant and mother. Measurements of vitamin D metabolites and intact PTH are required to recognize maternal hyperparathyroidism.