Assays for parathyroid hormone and their use in patients with end-stage renal disease.

New second-generation immunometric PTH assays have been developed. The assays measure full-length biologically active PTH(1-84) exclusively and do not detect amino-terminally-truncated PTH fragments, a feature that distinguishes them from first-generation immunometric PTH assays. Although few studies have been done thus far, second-generation immunometric PTH assays have not been shown to be superior to first-generation assays for the diagnostic assessment of patients with renal osteodystrophy. Plasma PTH levels obtained using first-generation-immunometric PTH assays continue to provide the most definitive guide to the management of renal bone disease because they are supported by abundant bone histology data. Additional work is needed to further characterize the utility of second-generation immunometric PTH assays as predictors of bone histology in patients with ESRD.