Familial benign hypercalcemia disclosed by nephrolithiasis

BACKGROUND: Diagnosis of familial benign hypercalcemia can be challenged by the association with a urinary lithiasis, which, in the presence of hyperc alcemia, will most frequently lead to affirm primary hyperparathyroidism. CASE REPORTS: We report the case of a 23 year-old patient who presented wit h a left ureteral stone composed of calcium oxalate. His serum total calciu m value was 2.92 mmol/l. Serum PTH value was inappropriately in the normal range (32 ng/l, normal values 10 to 58 ng/l). Hypercalcemia persisted despi te a subtotal parathyroidectomy and new investigation biochemical revealed familial benign hypercalcemia. CONCLUSION: This diagnosis is usually made fortuitously, since most patient s have few, a any, symptoms. A past familial history of hypercalcemia and s everal biochemical features (such as a reduced fractional excretion of calc ium, mild hypermagnesemia, and a normal serum inorganic phosphorus level) a re helpful clues to the diagnosis of familial benign hypercalcemia. In same cases, however, searching for an inactivating mutation of the extracellula r calcium-sensing receptor gene is necessary to distinguish this autosomal dominant disease from primary hyperparathyroidism. (C) 2000, Masson, Paris.