[An elderly case suspected of familial hypocalciuric hypercalcemia subsequent to manifestation of hypercalcemia].

Familial hypocalciuric hypercalcemia (FHH) is a relatively rare disease showing autosomal dominant heredity. Despite hypercalcemia, it shows a low urinary calcium excretion rate, and calcium clearance-creatinine clearance ratio. Since the serum calcium level does not increase to more than 12 mg/dl, this disease is basically asymptomatic and is incidentally found on medical examinations in many cases. However, it sometimes presents dangerous hypercalcemia and requires treatment. In this disease, parathyroidectomy is not sufficiently effective to cure hypercalcemia. We encountered a female patient with advanced age who presented marked hypercalcemia. Several examinations suggested FHH. While we had difficulty in controlling the serum calcium level, periodic administration of alendronate sodium hydrate, a bone resorption inhibitor, was effective. In this patient, the serum calcium level was normal on the examination about a year and a half before the appearance of symptoms, and hypercalcemia manifested itself in her advanced age, which is different from the usual course of FHH. This case presumably suggests that the pathophysiology of FHH is varied.