A patient with CHF will exhibit signs and symptoms that are somewhat nonspecific. These include edema, hypertension, shortness of breath, and weakness. Until recently the diagnosis of CHF was more difficult and lengthy, and often concluded by ruling out other conditions. However we now have biomarkers to assist in the diagnosis of CHF.
B-type natriuretic peptide (BNP) and/or the N-terminal fragment, NT-proBNP, are now routinely measured to diagnose CHF.
ProBNP is the precursor of BNP. It is released from the left ventricle myocardium in response to mechanical stretch. It may be strange to think of the heart as an endocrine organ, but it is. ProBNP is produced and released by the heart in response to overload or stretch due to pressure. This stretch is described as an increase in ventricular wall tension and is due to the pressure and volume overload that occurs in CHF. ProBNP is then enzymatically cleaved to produce BNP and NT-ProBNP. BNP is the active hormone composed of 32 amino acids. The N-terminal fragment is a longer chain of 76 amino acids; this fragment is biologically inactive. Studies indicate that NT-proBNP has the same clinical utility as BNP; measuring either one is appropriate for workup of CHF patients.
Besides diagnosing CHF, levels of BNP and NT-ProBNP correlate to the severity of heart disease, assist in detection of CHF where patients are asymptomatic, and differentiate patients whose pulmonary disease presents with symptoms similar to CHF.