In-clinic, quantitative NT-proBNP testing

B-type natriuretic peptide (BNP) is a 32-amino acid cardiac natriuretic peptide hormone that is secreted into the circulation by cardiac myocytes and fibroblasts in response to myocardial stress or stretch of the heart's walls due to increased volume and pressure. Its production is therefore significantly upregulated in cardiac failure.

BNP is secreted as a prohormone, proBNP, and then cleaved into the biologically active hormone, BNP, and the non active amino- terminus, NT-proBNP (76 amino acids); therefore, the concentration of either can be used to assess the magnitude of myocardial wall stress or stretch (Figure 1). However, the N-terminal pro-brain natriuretic peptide (NT-proBNP) is more stable and has a longer half-life than both the prohormone and BNP, making it a useable diagnostic analyte. A new quantitative point-of-care (POC) analyzer allows fast, onsite measurement of NT-proBNP, minimising preanalytical error and reducing variability.

This study aimed to analytically validate an NT- proBNP assay (Vcheck) according to American Society of Veterinary Clinical Pathology (ASVCP) and Clinical Laboratory Improvement Amendments (CLIA) specifications.

Precision and LOQ

Imprecision varied across concentrations with the lowest CV at the highest concentration as expected. Imprecision was considered acceptable with a coefficient of variation ranging from 9% at 4000 pmol/L to 12% at 1900 pmol/L.

The precision performance of Vcheck was verified, and performance was deemed acceptable for an immunoassay.

Accuracy

A comparison of the Vcheck assay with the Cardiopet NT-proBNP assay revealed an excellent correlation with minimal bias when preanalytical factors were controlled.

The linear equation was y=0.9x+37 (R2=0.9) with 95% Cis and a slope of 0.75-1.05 and an intercept of -150 to 224 (Figure 2).

When 61 samples were treated in a real- world, in-clinic setting, the R2 falls to 0.8 and it generated a significantly different linear equation, y=0.7x-52. So, onsite testing can minimize variability related to preanalytical error and provide clinically useful contemporaneous results.

For information on our No Charge Vcheck V200 Installation promotion please enquire through the Life Bioscience website. Conditions apply.