NT-pro-BNP is released when the walls of the heart’s chambers are stretched. Significantly elevated levels may be a marker for heart failure in those with corresponding symptoms. Levels increase with age and can be higher in women than men in general
Pro-brain (B-type) natriuretic peptide (NT-pro-BNP) is a fragment (and reflection) of brain natriuretic peptide (BNP), a neuroendocrine peptide. BNP is released when the heart’s chambers are stretched, reflecting increased pressure in the heart. This can be a sign of congestive heart failure. BNP may also be involved in other pathologies, including hypertension, atherosclerosis, myocardial infarction, and COVID-19.
The test is especially useful for identifying heart failure as a cause of shortness of breath (SOB). If SOB is accompanied by an elevated BNP or NT-pro-BNP, then it could be related to heart failure, which would be unlikely if BNP were low. Levels increase with age and tend to be higher in women than men. Laboratories may test BNP or NT-pro-BNP, and their recommended ranges differ. The conventional range for BNP is less than 100 pg/mL, while for NT-pro-BNP, it is below 300 pg/mL (Pagana 2021).
However, NT-pro-BNP, levels of 125 pg/mL or above may indicate heart failure in high-risk individuals. Moderately elevated levels may be clinically significant or predictive of future cardiac complications as well. Evaluation of data from 18,356 healthy participants with a mean age of 46.1 years revealed a median NT-pro-BNP level of 50 pg/mL. Levels rose as expected with age, likely partly due to a decreasing glomerular filtration rate. However, researchers did note that approximately 10% of healthy younger females had an elevated NT-pro-BNP of 125 pg/mL without apparent cardiac risk factors (Welsh 2022).
Ultimately, an elevated NT-pro-BNP above 125 pg/mL should be investigated further in a symptomatic or high-risk individual. Evaluation should include age, renal function, medical history, and cardiac risk factors. Females may have higher levels than males.
Although a level below 125 pg/mL is considered optimal, an NT-pro-BNP level alone is not considered diagnostic.
According to the Cleveland, Clinic:
A normal level of NT-proBNP, based on Cleveland Clinic’s Reference Range is:
- Less than 125 pg/mL for patients aged 0-74 years
- Less than 450 pg/mL for patients aged 75-99 years
If you have heart failure, the following NT-proBNP levels could mean your heart function is unstable:
- Higher than 450 pg/mL for patients under age 50
- Higher than 900 pg/mL for patients age 50 and older
References
Cleveland Clinic NT-proB-type Natriuretic Peptide. https://my.clevelandclinic.org/health/diagnostics/16814-nt-prob-type-natriuretic-peptide-bnp
Pagana, Kathleen Deska, et al. Mosby's Diagnostic and Laboratory Test Reference. 15th ed., Mosby, 2021.
Welsh, Paul et al. “Reference Ranges for NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) and Risk Factors for Higher NT-proBNP Concentrations in a Large General Population Cohort.” Circulation. Heart failure vol. 15,10 (2022): e009427. doi:10.1161/CIRCHEARTFAILURE.121.009427