Update on parathyroid hormone: new tests and new challenges for external quality assessment.

It is now 43 years since Berson and Yalow published the first radio-immunoassay (RIA) for parathyroid hormone (PTH) [S.A. Berson, R.S. Yalow, G.D. Aurbach, J.T. Potts, Immunoassay of bovine and human parathyroid hormone. Proc Natl Acad Sci U S A 49 (1963) 613-617] [1]. Since then, there have been marked advances in our understanding of this peptide hormone, its mechanism of action and biological regulation [J.T. Potts, Parathyroid hormone: past and present. J. Endocrinol. 187 (2005) 311-325] [2]. PTH has become a routine assay in tertiary care hospitals and is an essential element in the management of chronic kidney disease, parathyroid disorders and the investigation of abnormalities in calcium homeostasis. Despite continuing technological advances in PTH measurement, analyte heterogeneity remains a problem, while improved turnaround time and better precision are constantly escalating clinical demands. This mini-review begins with a brief update of current knowledge on PTH, followed by a summary of a recent Ontario-wide External Quality Assurance (EQA) survey, and concludes with comments on utilization trends, current and future.