[A rare cause of hypercalcaemia: familial hypocalciuric hypercalcaemia (author's transl)]

Two cases of familial hypocalciuric hypercalcaemia (FHH) in the same family are presented. This congenital disease is characterized by biochemical evidence of parathyroid toxicity but differs from primary hyperparathyroidism by the presence of normal parathyroid hormone levels. However, histomorphometric studies of transiliac bone biopsy specimens after double-labeling with tetracycline shows intensive remodelling of bone tissue with increase in osteoclastic resorption and osteoblastic apposition areas, all features identical with those observed primary hyperparathyroidism. The authors suggest hypersensitivity of target-organs (bones and kidneys) to parathyroid hormone as a probable physiopathological mechanism for FHH.