A novel mechanism for skeletal resistance in uremia

sured by most I-PTH immunoradiometric (IRMA) assays, givto prevent adynamic bone disease. ing erroneously high I-PTH values. We have developed a new IRMA assay in which the labeled antibody recognizes only the first six amino acids of the PTH molecule. Thus, this new IRMA assay (Whole PTH) measures only the biologically active 1-84 Parathyroid hormone (PTH), a single-chain polypepPTH molecule. tide of 84 amino acids [1], plays a critical role in the Methods. Using this new IRMA assay (Whole PTH) and the Nichols “intact” PTH assay, we compared the ability of regulation of mineral metabolism. Ionized calcium, caleach assay to recognize human PTH (hPTH) 1-84 and hPTH citriol, and phosphorus are the three major regulators 7-84 and examined the percentage of non-1-84 PTH in circula- of PTH homeostasis in humans. tion and in parathyroid glands. Possible antagonistic effects of The human PTH gene is located on the short arm of the 7-84 PTH fragment on the biological activity of 1-84 PTH chromosome 11. The coding region spans more than 4