Interactions between liver and parathyroid hormone.

Abstract

In the past decade advances have been made in the understanding of the metabolism of parathyroid hormone and the interpretation of the findings of fragments of parathyroid hormone in peripheral blood. Early studies1,2 with radioimmunoassay gave different results in patients with primary hyperparathyroidism. It was thought that the radioimmunoassay for parathyroid hormone measured in blood the peptide secreted by the parathyroid glands. However, Berson and Yalow3 demonstrated that parathyroid hormone in plasma of patients was heterogeneous and differed immunologically from the hormone extracted from parathyroid glands of humans. Using different antisera they clearly demonstrated the presence of fragments of the PTH molecule with various half lives such that some fragments rapidly become undetectable after parathyroidectomy while other fragments had prolonged half lives in circulation. They also demonstrated that the half life of immun-oreactive PTH was markedly prolonged in patients with uremia. Subsequently it became apparent that intact PTH and the biologically active amino-terminal fragments have short half lives in the circulation (less than 5 minutes) while carboxy-terminal fragments have much longer half lives (30 to 40 minutes).