Background: N-terminal pro-B type natriuretic peptide (NTpBNP) is a potential marker of cardiac failure.
Methods: The Roche ElecsysTM 1010 and 2010 assays for NTpBNP were evaluated for precision, sample stability, and correlation between sample types and with other natriuretic peptides. Samples from 290 individuals aged 45-89 years with no cardiovascular risk factors, renal failure, electrocardiogram changes, evidence of structural abnormalities, or wall motion abnormalities on echocardiography and with an ejection fraction >50% were used to provide reference NTpBNP ranges.
Results: The intra-assay imprecision was <10% across the analytical range and >3% at all concentrations analysed <30 ng/L. Inter-assay imprecision was 5.3-6.7% on the Elecsys 1010 and 4.4-5.0% on the Elecsys 2010, in the range 380-13000 ng/L. There was no statistically significant change in NTpBNP following storage in whole-blood samples at room temperature for 24 h before centrifugation; serum samples at room temperature for 7 days, at 4°C for up to 11 days on clot-activation gel or 22 days separated from the gel. NTpBNP concentrations were stable throughout five freeze-thaw cycles. There was a close correlation between NTpBNP concentrations in matched serum, EDTA plasma and lithium-heparin plasma samples. NTpBNP and BNP were more closely associated than were N-terminal proatrial natriuretic peptide and NTpBNP. This association was stronger at lower concentrations. NTpBNP concentrations increased with age, with values higher in women than men.
Conclusions: NTpBNP is a stable molecule that can be measured easily and precisely using the Roche Elecsys 1010 or 2010 immunoassay analysers.
