Intrauterine hyperparathyroidism. Postmortem findings in two cases.

Intrauterine hyperparathyroidism is a self-limited condition seen in the neonate born of a mother with poorly controlled hypoparathyroidism. In this report, we describe the histologic findings in bone and parathyroids in twin infants with this condition who died from other causes. The skeleton showed osteopenia with evidence of increased bone turnover and defective mineralization, and there was parathyroid gland hyperplasia of the water-clear cell type. One twin died at birth, and the histologic findings were indistinguishable from those of infantile primary hyperparathyroidism; but the second twin, dying at 3 months of age, demonstrated noticeable improvement in the bone and parathyroid abnormalities.