Background The neonate is susceptible to hypocalcemia from a variety of etiologies. At particular risk is the low birth weight or premature infant, those born to diabetic mothers and those who have increased perinatal stress.
Case Report We report a two week old full term male infant with a 7 day history of twitching, jerking movements of the extremities. The mother reported respiratory and feeding difficulties one day prior to admission. The history was negative for fever, lethargy, emesis or diarrhea. Laboratory analysis revealed a serum calcium 6.3 mg/dL, ionized calcium 0.9 mmol/L, phosphorus 11.3 mg/dL, magnesium 1.2 mg/dL, and albumin 3.2 g/dL. The rest of her metabolic panel, liver function studies, CBC, CRP, chest x-ray, and CT scan of the brain were all within normal limits. The infant was admitted to the PICU and treated with a calcium gluconate infusion. Serum calcium increased to 10.6 mg/dL and phosphorus to 7 mg/dL. Symptoms resolved within 2 days. He was sent home on oral calcium supplements. Further investigation for the hypocalcemia of the infant revealed normal levels of PTH, vitamin D, and thyroid function studies. A workup on the mother was performed and demonstrated increased serum calcium 12.3 mg/dL, phosphorus 1.9 mg/dL, PTH 323 pg/dL (normal 15-75) and vitamin D 10 mg/mL. An ultrasound of the neck and radiothallium scanning revealed a parathyroid adenoma of the right superior gland.
Discussion Neonatal hypocalcemia and tetany may be observed as a result of maternal hypercalcemia or hyperparathyroidism. There will generally be a prolonged but temporary suppression of parathyroid function in the infant. Hypocalcemia in a full term baby with no complications in pregnancy or perinatal history should prompt an investigation in the mother.