NT-proBNP

Heart failure is also called congestive heart failure. If you have this condition, your heart has trouble pumping enough oxygen-rich blood to meet your body's needs.

Two types of natriuretic peptides can be measured to check for possible heart failure. Brain natriuretic peptide (BNP) is a protein that's a type of hormone. Your heart makes and releases BNP into your bloodstream when it's working harder than normal to pump blood. The BNP tells your blood vessels to open wider and your kidneys to get rid of water and salt through urine (pee). This helps reduce the workload on your heart by lowering blood pressure and reducing the amount of blood your heart has to pump. N-terminal pro b-type natriuretic peptide (NT-proBNP) is a protein that's an "ingredient" for making the BNP hormone. Like BNP, your heart makes larger amounts of NT-proBNP when it has to work harder to pump blood.

It's normal to have some BNP and NT-proBNP in your bloodstream. But higher than normal levels for your age and sex may be a sign of heart failure.

NT-proBNP can also be used to gauge a person's risk after a heart attack or in people with heart failure or stable coronary artery disease, helping providers estimate the chance of future heart problems.

The meaning of your test results will depend on your age, sex, medical history, family history, and the results of other tests. A BNP or NT-proBNP test alone can't diagnose the cause of your symptoms. But in general, if you have symptoms that could be caused by heart failure, normal results on a BNP or NT-proBNP usually mean that you're unlikely to have heart failure, while higher than normal levels of BNP or NT-proBNP mean that you could have heart failure.

For NT-proBNP specifically, a value below 300 pg/mL makes acute heart failure very unlikely. The level that suggests heart failure goes up with age: roughly above 450 pg/mL under age 50, above 900 pg/mL between 50 and 75, and above 1,800 pg/mL over age 75. Reduced kidney function tends to push these numbers higher, so your provider will take that into account.

If you have obesity, your weight may affect the accuracy of your test results, making your levels lower than they really are. If your provider suspects heart failure, you may have other heart health tests even if your BNP or NT-proBNP levels are normal.

In most cases, the higher the level of your test results, the more serious your heart failure may be. But other health conditions can increase BNP and NT-proBNP levels. That's why your medical history is important for understanding whether high test results mean you have heart failure. Other conditions that can cause high levels of BNP and NT-proBNP include kidney failure, other types of heart disease (including conditions that affect your heart valves or heart muscle), and certain lung disorders.