Parathyrin (parathyroid hormone): metabolism and methods for assay.

Parathyrin (parathyroid hormone) radioimmunoassay is a commonly ordered endocrine assay. I discuss here of the metabolism of the hormone and the effect information on this metabolism has had on the development of radioimmunoassays for parathyrin. Although radioimmunoassay is the most widely accepted technique for the routine assay for parathyrin, "high-performance" liquid chromatography, cytochemical bioassay, and homologous bioassay have also been developed for this analyte. Accordingly, I briefly review the clinical utility of these assays in terms of their ability to assess the functional activity of the parathyroid gland.