Neonatal hypocalcaemia associated with maternal hyperparathyroidism. New pathogenetic observations.

A 32-day-old male infant had hypocalcaemic convulsions associated with asymptomatic maternal hyperparathyroidism. Very low total and ionised serum calcium, increased serum phosphate, and normal serum parathyroid hormone (PTH) and 25-hydroxycholecalciferol (25-OHD3) concentrations were found at admission. After treatment with calcium and vitamin D, serum PTH and 25-OHD3 concentrations increased markedly before serum calcium levels returned to normal perhaps indicating an inability to convert 25-OHD3 to the metabolically active 1,25-dihyroxyvitamin D3 during the hyperphosphataemic state. Treatment with 1,25-dihdroxyvitamin D3 or its analogues is recommended.