What BNP and NT-proBNP are
BNP (B-type natriuretic peptide) is a hormone made by the heart. It widens blood vessels and helps the kidneys remove salt and water, which eases the heart's workload. NT-proBNP is a related protein that the body uses as an ingredient to make BNP.
Both rise when the heart is under strain. Your clinician decides which one to test. They have different normal ranges, so a result is read against the cutoffs for that test.
Why the test is ordered
- Shortness of breath that could be a sign of heart failure.
- Swelling in the legs, feet, belly or neck veins, tiredness, cough, or trouble sleeping lying flat.
- Known heart failure, to gauge severity or check whether worse symptoms mean the condition is getting worse.
- After a heart attack or unstable angina, in some cases, for monitoring.
Typical BNP and NT-proBNP levels
| Test | Usually normal | May suggest heart failure |
|---|---|---|
| BNP | Under 100 pg/mL | Over 100 pg/mL |
| NT-proBNP, under age 75 | Under 125 pg/mL | Over 900 pg/mL |
| NT-proBNP, over age 75 | Under 450 pg/mL | Over 900 pg/mL |
There is no Gabriel optimal range for BNP. It is a diagnostic test read in context, not a wellness marker to push lower.
What else can change your result
- Kidney disease can raise BNP and NT-proBNP.
- Other heart problems, such as valve disease or heart muscle disease, can raise them.
- Lung problems, such as a blood clot in the lung (pulmonary embolism) or high blood pressure in the lungs, can raise them.
- Severe infection (sepsis) can raise BNP.
- Obesity can make levels read lower than they really are, so a normal result may still need follow-up if heart failure is suspected.
Because so many things move these numbers, a BNP test alone can't say what is causing your symptoms. Clinicians usually add an EKG, an echocardiogram, and kidney and liver blood tests such as a CMP and eGFR.
What to ask after a high result
- What is likely causing it, given my kidneys, lungs and other results?
- Which heart tests come next, such as an echocardiogram?
- Should I recheck it, and with the same test (BNP or NT-proBNP) so the numbers compare?
- What should I watch for at home, such as weight gain or more swelling?
Call 911 for chest pain or pressure, severe or sudden shortness of breath, bluish lips or fingers, or fainting. Get same-day care for new or quickly worsening swelling in your legs, feet or belly, or if you can no longer sleep lying flat.
Common questions
What is a normal BNP level?
Cleveland Clinic lists a normal BNP as under 100 pg/mL. Labs differ slightly, and your clinician reads it with your age and kidney function.
What is the difference between BNP and NT-proBNP?
BNP is the active hormone; NT-proBNP is a fragment released when it is made. Both rise when the heart is strained, but they have different normal ranges, so each is read against its own cutoffs.
Does a high BNP always mean heart failure?
No. Kidney disease, other heart conditions, lung problems such as a blood clot, and severe infection can also raise it. More tests are needed to find the cause.
Can a normal BNP rule out heart failure?
A normal result usually makes heart failure unlikely. Obesity can lower BNP, though, so clinicians may test further if symptoms still point to the heart.
Can I order a BNP test myself?
It is used to look into symptoms such as shortness of breath or swelling, and the result needs a clinician to read it with your history. If you have symptoms, see a clinician rather than testing on your own.
Sources
- Natriuretic Peptide Tests (BNP, NT-proBNP) MedlinePlus, U.S. National Library of Medicine
- Brain natriuretic peptide test MedlinePlus, U.S. National Library of Medicine
- B-Type Natriuretic Peptide (BNP) Test Cleveland Clinic
- Heart Failure: Diagnosis National Heart, Lung, and Blood Institute
- Heart Failure: Symptoms National Heart, Lung, and Blood Institute
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.