[Familial hypercalciuric hypercalcemia]

Abstract

Familial hypocalciuric hypercalcemia (FHH) or familial benign hypercalcemia is an autosomal dominant inherited disorder of calcium metabolism. It is characterized by lifelong asymptomatic hypercalcemia associated with a relative hypocalciuria and a tendency to hypermagnesemia. The biochemical features of this disorder are difficult to distinguish from mild primary hyperparathyroidism. Several patients have therefore been operated upon for hyperparathyroidism with no effect on calcium levels. The most important diagnostic criterion of FHH in a single individual is the demonstration of asymptomatic hypercalcemia in other family members including children. The pathophysiology of the disorder is unknown. A genetic defect of cellular calcium transport leading to a disturbed regulation of extracellular calcium by parathyroid glands and kidneys has been suggested. The hypercalcemia in this disorder is asymptomatic, usually without complications and does not require treatment. Partial parathyroidectomy has no effect on the hypercalcemia. However, it is important to diagnose this condition in order to avoid unnecessary neck explorations. Two complications have been described in some families: pancreatitis and neonatal primary hyperparathyroidism. The recommended management of these complications is total parathyroidectomy.