Technical Note: Discordance Between Point of Care (POCT) BNP and Laboratory-Based NT-proBNP Values at Decision Cut-off in Some Patients - POCT BNP Values Below Cut-off Should be Interpreted with Caution.

Abstract

Objective: Both B-type natriuretic peptide (BNP) and NT-pro BNP are markers for heart failure. In our hospital and other institutions, both point of care (POCT) BNP and clinical laboratory-based NT-Pro BNP test are used interchangeably by clinicians. We evaluated any discrepancy between these tests at decision cut-off point.

Method: In a three-month period, in 120 patients, both POCT BNP and NT-proBNP were ordered at the same time and we evaluated these results.

Results: We observed significant discordant results in 14 of these patients where POCT BNP concentrations were normal, but NT-pro BNP concentrations were elevated. Moreover, correlation between POCT BNP and NT-proBNP concentrations was also poor and in some cases NT-proBNP values were 15-fold higher than BNP.

Conclusions: Because of this significant discordance, if both tests are ordered for initial diagnosis, POCT BNP result should be interpreted with caution if below the cut-off. Moreover, if only POCT BNP is ordered it may be normal in some patients with heart failure.