Comparison between intact and bioactive parathyroid hormone assays in patients with severe heart failure

Parathyroid hormone (PTH) is a major systemic calcium-regulating hormone. Recent evidence has suggested that measurement of PTH might provide complementary information for the diagnosis and risk stratification of patients with heart failure (HF). The aim of our study was to compare intact and bioactive PTH assays in patients with severe heart failure. The following measurements were carried out in blood samples from 73 patients with severe heart failure: bioactive PTH (1–84) assay, intact PTH assay, non-PTH (1–84), 25-hydroxyvitamin D, B-type natriuretic peptide (BNP), N-terminal proBNP (Nt-proBNP), Galectin-3 and high sensitive troponin T (hsTnT). The correlation between intact and bioactive PTH assays was very high in HF patients. However, the bioactive PTH concentrations were lower than those measured with the intact assay. Intact and bioactive PTH as well as non-PTH (1–84) was significantly and positively correlated to BNP, Nt-proBNP, and galectin-3 but not to hsTnT. The strongest relationships with these cardiac biomarkers and with cardiovascular death were observed with the bioactive PTH assay. The PTH concentrations obtained with intact and bioactive assays are not comparable in patients with severe HF. The specificity of PTH assays might therefore impact on the potential diagnosis and prognosis values of PTH testing in patients with heart failure. ► First comparison of intact and bioactive PTH assays in heart failure (HF) patients ► Concentrations of intact and bioactive PTH assays are not comparable in HF patients. ► Intact and bioactive PTH assays are related to biomarkers of HF worsening. ► The specificity of PTH assays might impact on the management of HF patients.