Neonatal severe hyperparathyroidism due to compound heterozygous mutation of calcium sensing receptor (CaSR) gene presenting as encephalopathy.

The authors report a 14-d-old neonate who presented with lethargy, polyuria and dehydration and was found to have severe hypercalcemia with hyperparathyroidism. This neonate was treated with saline hydration, diuresis and injection pamidronate. Genetic analysis revealed a compound heterozygous mutation of CaSR.