BNP and NT-proBNP
Also written as: BNP, NT-proBNP, B-type natriuretic peptide, brain natriuretic peptide
Hormones the heart releases when its walls are stretched, used to assess strain on the heart.
What it measures
BNP is a hormone that the heart's pumping chambers release when their walls are stretched by pressure or extra fluid. NT-proBNP is an inactive fragment produced at the same time. A lab measures one or the other, and the two are reported on very different scales.
Why a doctor orders it
Most often ordered when breathlessness, swelling, or fatigue raises the question of heart failure, meaning the heart is not pumping as efficiently as it should. It is also used to follow known heart conditions over time.
What is generally associated with a higher result
Broadly associated with stretch or strain on the heart, including heart failure, but also with older age, kidney disease, atrial fibrillation (an irregular heart rhythm), and some lung conditions. Levels also tend to run higher in women and in older adults who have no heart problem at all.
What is generally associated with a lower result
Broadly associated with a low likelihood of significant strain on the heart. Levels can also run lower than expected in people with higher body weight.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Age - levels rise naturally as people get older
- Body weight - levels tend to run lower at higher weights
- Kidney function, which especially influences NT-proBNP
- Which version the lab measured - BNP and NT-proBNP numbers are not interchangeable
- Certain common heart and blood pressure medicines, which can shift measured BNP
Questions to take to your appointment
- Was BNP or NT-proBNP measured, since the two use different scales?
- Could my age, weight, or kidney function be shifting this value?
- Would an echocardiogram (an ultrasound of the heart) add useful information here?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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