[A rare cause of hypercalcemia: familial hypocalciuric hypercalcemia].

BACKGROUND: Familial hypocalciuric hypercalcemia is a rare disease with autosomal dominant transmission. Its basic defect is unknown and it requires no treatment. CASE REPORT: 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. CONCLUSIONS: This asymptomatic familial hypercalcemia has the characteristics of familial hypocalciuric hypercalcemia. There was no associated endocrine disorder. Screening of family members is worthwhile.