Primary hyperparathyroidism in a hypothyroid child.

Congenital hypothyroidism may result in severe mental retardation if this condition is not diagnosed in the neonatal period. Primary hyperparathyroidism in children is even more uncommon, and by 1977 had been reported in only 60 children under the age of 16 years. To our knowledge, we are reporting the first child with both congenital hypothyroidism and primary hyperparathyroidism. Because the normal anatomic relationship of the parathyroid glands to the thyroid gland was absent, preoperative localization studies were necessary. Ultrasonography, radionuclide scanning, and magnetic resonance imaging all indicated a right paratracheal mass in the region where the right lobe of the thyroid gland should be located. At operation, a single, enlarged parathyroid gland that measured 1.5 X 1.2 X 0.5 cm and weighed 500 mg was removed. The discharge serum calcium level was 9.3 mg/dl and has remained normal 2 years later.