PTH determination in hemodialyzed patients-A laboratory perspective

Parathyroid hormone (PTH) is a key player of bone remodelling in patients suffering from Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Serum PTH concentrations are thus frequently measured in CKD patients. Nevertheless, this determination is far from simple. PTH stability can be an issue and degradation of the peptide can be important if storage is not properly done. Biologically active PTH circulates together with fragments, which can be detected by some immunoassays. There is, up to now, no standardization of the assays available on the market, which can lead to some confusion when patients are followed with different methods. The upper end of the reference ranges provided by some manufacturers have not been properly established and are sometimes far too high. Finally, PTH can be oxidized in vivo and thus become inactive, while still quantified by immunoassays. In this Editorial, we will try to highlight some of these issues on PTH measurement.