Familial benign hypercalcemia (hypocalciuric hypercalcemia). Clinical and pathogenetic studies in 21 families.

Familial benign hypercalcemia (hypocalciuric hypercalcemia) was diagnosed in 125 members of 21 families. The syndrome was generally characterized by autosomal dominant inheritance of symptomless, nonprogressive hypercalcemia with normal serum immunoreactive parathyroid hormone concentrations, parathyroid glands that had normal gross and histologic features, relatively low urinary excretion of calcium, and failure to achieve normocalcemia after subtotal parathyroidectomy. Affected persons had normal longevity and no discernible increase in other medical problems except gallstones. The parathyroid glands were not seen using high-resolution ultrasonography. Plasma calcitonin and calcitriol levels were normal or low. Skeletal mass was normal as assessed by photon absorptiometry of the radius and lumbar spine, and fractures were not more frequent. Familial benign hypercalcemia or hypocalciuric hypercalcemia is a distinctive heritable syndrome that should always be considered in the differential diagnosis of asymptomatic hypercalcemia.