BIOLOGICALLY ACTIVE PARATHYROID HORMONE IN FAMILIAL HYPOCALCIURIC HYPERCALCAEMIA

Abstract
Biologically active PTH ([parathyroid hormone] bio-PTH) was assayed by the cytochemical bioassay in 5 members (3 affected) of a family with typical features of familial hypocalciuric hypercalcemia (FHH). Carboxy-terminal immunoreactive PTH was undetectable and bio-PTH was within the normal range in all the subjects regardless of whether they were hypercalcemic. Increased biological activity of circulating PTH evidently cannot account for the hypercalcemia of FHH.