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Abstract: TH-PO216

Evaluation of Intact and Biointact PTH Assays in Chronic Hemodialysis Patients

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Berner, Carolin, Medical University Vienna, Vienna, Austria
  • Marculescu, Rodrig, Medical University of Vienna , Vienna, Austria
  • Sliwka, Henrik, Medical University of Vienna , Vienna, Austria
  • Bieglmayer, Christian, Medical University of Vienna, Vienna, Austria
  • Hecking, Manfred, Medical University of Vienna, Nephrology & Dialysis, Vienna, Austria
Background

Clinical management of chronic kidney disease - mineral and bone disorder is largely based on parathyroid hormone (PTH) concentrations, measured at regular intervals. The existence of PTH fragments, detected by first and second generation (“intact”) PTH (i-PTH) assays, led to the development of third generation (“biointact”) whole PTH (w-PTH) assays detecting only full length PTH. Despite efforts to use only w-PTH assays, i-PTH assays, which are usually less costly, are still being used and marketed, such that it may be indispensable to convert PTH values from one assay to another. We aimed at assessing the technical performance of a novel i-PTH assay, in comparison to 2 widely used w-PTH assays and to another i-PTH assay.

Methods

PTH levels of 134 patients on chronic hemodialysis were measured at 2 timepoints within 3 months, using: the novel new i-PTH assay by Siemens Healthcare (SH) and Roche Diagnostic (RD), respectively; the w-PTH assay by RD and DiaSorin (DS), respectively. All concentrations were measured in pg/ml by automated analyzers: Advia Centaur CP (SH), Cobas e 602 (RD) and Liaison XL (DS). Statistical methods included Passing-Bablok regression analyses and Bland Altmann plots.

Results

The i-PTH SH was slightly higher calibrated than i-PTH RD. Compared with w-PTH assays, the i-PTH SH assay yielded 2.5-fold higher results, while i-PTH RD was about 2-fold higher. Among the w-PTH(1-84) assays a rather good concordance was observed, with a mean bias of 12 ± 45.6 pg/mL (±2 SD) by Bland Altmann plots. In contrast, there was a substantial bias of -88.7 ± 183.4 pg/mL between the two iPTH assays (RD minus SH).

Conclusion

The table provided above enables method conversions, which are of interest, if a laboratory switches the assay or if a patient changes the treatment center.

Funding

  • Commercial Support