Description

Abstract
The natriuretic peptides are a family of ring shaped
vasoactive hormones showing considerable sequence
homology. Four natriuretic peptides have been described,
named A-D type of which two have current clinical
relevance, atrial natriuretic peptide (ANP) and B type
natriuretic peptide (BNP). ANP is found in the atria of the
heart. stored as a prohormone. BNP, originally discovered in
the porcine brain, is found in the ventricles of the heart.
BNP is produced by direct synthesis in response to the degree
of ventricular stretch. Interest in natriuretic peptide
measurement was originally as a diagnostic and
management tool for patients with cardiac failure. Studies
have shown that clinical assessment, ECG and chest
radiography have limited value for diagnosis of heart failure,
so BNP might fill the need for a diagnostic test for cardiac
failure that is cheap and widely available, particularly for
primary care physicians. There has been development of
assays for N Terminal pro BNP(NTpBNP) and BNP
suitable for routine clinical use. Three systems are currently
available, a point of care system (Triage, Biosite) and two
assays for use on high throughput laboratory immunoassay
systems. These are the NTpBNP assay from Roche
Diagnostics and the BNP assay from Bayer Diagnostics. A
number of large studies have now been published and the role
of BNP and NTpBNP for diagnosis and management in
cardiac disease is beginning to be delineated. From these it
would appear that measurement of either BNP or
NTpBNP can be used interchangeably. Studies of
BNP/NTpBNP measurement in cardiac failure have
examined their role for diagnosis of both chronic and acute
heart failure patients and shown them to be very effective
diagnostic tests. A number of small studies have examined
the role of BNP measurement in monitoring treatment in
CCF. In addition, studies have examined the role of
natriuretic peptides in acute coronary syndromes. They
suggest that a single sample for BNP/NTpBNP taken at or
around admission provides further additional information for
risk stratification. The reference ranges for BNP/NTpBNP
have been defined by the manufacturers and are age and sex
specific, as well as increasing with impaired renal function
due to reduced clearance. BNP/NTpBNP values increase
with age and are higher in women and men. The major
value of NTpBNP/BNP measurements is as a rule out
test. A normal value excludes disease, but an elevated value
only confirms a diagnosis of myocardial dysfunction.