BNP, as an active protein hormone, has a short biological half-life of around 20 minutes. The inactive fragment NT-ProBNP, has a longer half-life of 1-2 hours. Both are increased in CHF and both levels correlate to the severity of condition. These two hormones are also used as prognostic indicators in ACS. Studies have shown that higher levels predict cardiac mortality and adverse cardiac events in patients with ACS.
Because of its longer half-life, there are advantages to measuring NT-ProBNP over BNP. If a CHF patient is receiving exogenous and synthetic BNP for treatment, BNP levels may be affected while NT-ProBNP will not be affected. However, NT-ProBNP is thought to be primarily cleared by kidneys and therefore falsely elevated in severe renal disease.