[A rare cause of hypercalcemia: familial hypocalciuric hypercalcemia]

Familial hypocalciuric hypercalcemia is a rare disease with autosomal dominant transmission. Its basic defect is unknown and it requires no treatment.

A 4 month-old girl was admitted for unexplained crying. She was found to have hypercalcemia (2.8 mmol/l) and later values of blood calcium were 3, 3.1 and 3 mmol/l. The serum free ionic calcium level was also elevated. The serum concentrations of protein, phosphorus, magnesium and the alkaline phosphatase activity were all normal. Serum concentrations of 25-(OH)-D3, 1.25-(OH)-2-D3 and PTH were also normal. The urinary calcium/creatinine ratio was normal and the urinary calcium excretion was 1.08 mg/kg/d. Screening of family members showed hypercalcemia in the father (2.8 mmol/l) and a brother aged 7 years (2.9 mmol/l). Short-term treatment with disodium etidronate lowered the serum calcium level to normal, but hypercalcemia reappeared once the treatment was discontinued.

This asymptomatic familial hypercalcemia has the characteristics of familial hypocalciuric hypercalcemia. There was no associated endocrine disorder. Screening of family members is worthwhile.