Asymptomatic hypercalcemia due to an ectopic parathyroid adenoma in an 8-year-old boy

The diagnosis of primary hyperparathyroidism in children is often delayed a nd is usually based on symptoms of hypercalcemia rather than abnormal labor atory values alone. We report the case of an g-year-old boy with hypercalce mia, hypophosphatemia and mildly, but inadequately elevated intact parathyr oid hormone (iPTH) who presented without any symptoms of hyperparathyroidis m. Although imaging studies were misleading and four normal parathyroid gla nds were found intraoperatively, exploration of the thymus revealed an ecto pic parathyroid adenoma. After removal of the ectopic gland, a rapid iPTH I mmunoassay proved immediate normalization of iPTH. This is the first report of sporadic isolated primary hyperparathyroidism diagnosed in an asymptoma tic child on the basis of hypercalcemia and hypophosphatemia.