Familial hypocalciuric hypercalcaemia is a rare autosomal dominant disorder which has only recently been recognised in which there is reduced urinary calcium excretion - less than 200 mg (5mmol) per 24 hours - in the presence of hypercalcaemia (1)
There may be hypermagnaesaemia with normal or minimally elevated PTH.
Diagnosis is made on family history and determination of low urinary calcium clearance - unlike hyperparathyroidism.
- a more up-to-date reference suggests
that the diagnosis of familial hypocalciuric hypercalcaemia depends on assessment
of urine calcium concentrations and measurement of the calcium/creatinine (Ca/Cr)
clearance ratio in the patient and family members with hypercalcemia
- in familial hypocalciuric hypercalcaemia, Ca/Cr clearance ratio is typically less than 0.01 (2)
No treatment is indicated as there is no response to parathyroidectomy. The prognosis is excellent.
There is a very rare autosomal recessive form which is lethal unless parathyroidectomy is performed.
- Famialial hypocalciuric hypercalcaemia. Lancet 1982; 319(8270): 488-489
- Younes NA et al. Laboratory screening for hyperparathyroidism.Laboratory screening for hyperparathyroidism. Clin Chim Acta. 2005 Mar;353(1-2):1-12. Review.