Recent advances in parathyroid disease and parathyroid hormone assays.

Parathyroid hormone (PTH) regulates extracellular calcium. The physiology and pathology of PTH and the many circulating fragments of PTH are reviewed. Various PTH assays have been used, leading to the now standard intact PTH (iPTH). The recently discovered 7-84 fragment may have profound implications in PTH measurement and management, particularly in renal-failure patients. Newer assays measuring true PTH, exclusive of this fragment, are appearing on the market and may have use in monitoring calcitriol analogue therapy and other settings. Rapid PTH assays have application as intraoperative measures of success during excision of parathyroid adenomas.