Tuesday December 20, 2005
BNP or Pro-BNP ?
Although BNP and NT-proBNP are breakdown products of same parent peptide but in laboratory BNP and NT-proBNP are 2 different tests with 2 different ranges of normal, designed for same reason. Psychologically we are so prone to use BNP that we may have NT-proBNP value in our hand but read it as BNP. There is no conversion formula. NT-proBNP is 2.5 times heavier peptide than BNP (76 amino acids vs 32 amino acids) with 3- 6 times longer half life (120 minutes vs 20 minutes). NT-proBNP get solely excreted via kidney but BNP gets only partially excreted via Kidney. In short NT-proBNP of 400 may means nothing but may be significant if its BNP. Please check: Is it BNP or NT-proBNP ?. It may require different clinical approach though for same clinical problem. Both tests have very good negative predictive value for LV-dysfunction.
Do you know which assay your laboratory use?
References: Click to get abstract/article
1. EDUCATIONAL COMMENTARY - BNP - American Proficiency Institute – 2002 3rd Test Event
2. Using BNP to diagnose, manage, and treat heart failure - CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 70 • NUMBER 4, APRIL 20033. NT-ProBNP - referencelab.clevelandclinic.org May 2004
4. Application of NT-proBNP as a Diagnostic Marker of Cardiac Disease - available free at medscape with CME with free registration at medscape.com
5. NT-proBNP test results comparable to those of BNP blood test in patients with kidney disease - rxpgnews.com