Comments on plasma parathyroid hormone levels and their relationship to bone histopathology among patients undergoing dialysis.

Measurements of the concentration of parathyroid hormone (PTH) in serum or plasma are used widely for the initial diagnostic assessment of patients with renal bone disease, to monitor disease progression, and to gauge responses to treatment. Several analytical methods are used to measure plasma PTH levels, and a variety of PTH assays are available. Each is unique technically, and the results obtained with any particular method often differ from those determined in the same biological sample using other assays that utilize qualitatively different reagents. It is imperative that clinicians recognize the potential impact of methodological differences among PTH assays on the biochemical results provided. Numerous claims have been made recently about the utility of new methods for measuring plasma PTH, about the value of estimating the amounts of amino-terminally truncated PTH fragments in plasma, and about the shortcomings of existing guidelines for the acceptable range of plasma PTH concentrations that correspond to optimal bone health among patients with chronic kidney disease. These matters serve as the focus for the current commentary.