A patient with congestive heart failure (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 was based on ruling out other conditions. Indeed, renal failure can present in a very similar fashion to congestive heart failure. Thankfully, we now have biomarkers to assist in the diagnosis of CHF.
B-type natriuretic peptide (BNP) and 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 of the heart in response to mechanical stretch. The heart is not always thought of as an endocrine (hormone-producing) organ, but it is. ProBNP is produced and released by the heart in response to volume overload or stretch due to pressure. This stretch is due to an increase in ventricular wall tension because of the 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 measuring NT-proBNP has the same clinical utility as BNP; measuring either one is appropriate for the workup of CHF patients.
Besides diagnosing CHF, levels of BNP and NT-proBNP correlate to the severity of heart disease, assist in the detection of CHF where patients are asymptomatic, and differentiate patients whose pulmonary disease presents with symptoms similar to CHF.
