Brain Natriuretic Peptide (BNP)

If your healthcare provider suspects heart failure, an inability of the heart to properly pump blood throughout the body, they may call for a BNP, which is an abbreviation for the hormone, brain natriuretic peptide. The BNP is a test that measures levels of this hormone in the bloodstream.

BNP is a hormone produced by the heart in response to excess cardiac stress, especially during heart failure. BNP helps to reduce cardiac stress by increasing salt and water excretion by the kidneys, and dilating blood vessels.

Though traces are always present during healthy cardiac function, elevated amounts of BNP in the blood implies insufficient pumping activity, the underlying cause of heart failure. This can also be a sign of other problems, such as hypertension (high blood pressure) and cardiac hypertrophy (enlarged heart muscles), as well as kidney conditions.

Given how instrumental BNP is as part of diagnosis of heart failure, it’s important to understand what healthcare providers mean and what they’re looking for when they call for BNP.    

The BNP Blood Test

The BNP measurement is a blood test that you may see in your electronic medical records, or that your healthcare provider may discuss with you.

The BNP blood level is almost always elevated during heart failure, and can be a useful test in confirming or ruling out this condition.

A related blood test, the NT-proBNP level, may also be measured. NT-proBNP is a by-product of BNP production, and in some people, it can be a more sensitive marker for the presence of heart failure.

When BNP Is Recommended

BNP may be part of a panel of blood tests and other types of tests employed in diagnosing the presence of and tracking the progression of heart failure.

Cardiologists will call for it when they suspect this condition but want to make sure another condition isn’t causing symptoms. In addition, this test will be employed to make sure treatments for heart failure are effective in resolving the problem.   

What You Should Know About BNP

How It Is Done

BNP is part of a panel of blood assessing the composition of blood. A healthcare professional uses a needle to draw a small sample of blood from a vein, usually in the arm.

To ease sample collection, a band may be tied around the upper arm, and you may be asked to make a fist, causing your veins to pop out. Once enough blood is drawn into a tube, it’s sent to the lab for clinical testing.

What It Can Tell You

During heart failure, excess blood remains in the chambers of the heart, building up pressure. In response, the BNP hormone is released from the walls of these chambers, which helps dilate other vessels and arteries, easing this pressure.

BNP is also a biomarker, or measurable indicator, of cardiac hypertrophy, which is the abnormal growth of heart muscles. It often precedes and/or accompanies heart failure. Basically, over-development of this organ—leading to spikes in BNP levels—means that it’s struggling to properly circulate blood through the body.

Primarily, BNP has three purposes:

• Detecting heart failure: This test will catch elevated BNP levels associated with heart failure when this condition is suspected.
• Ruling out heart failure: BNP is even more effective at ruling out heart failure when patients complain of symptoms associated with the condition.
• Tracking progress: During the course of treatment for heart failure, BNP may be used to assess progress. Generally, healthcare providers want to see these numbers going down.

Concerns With Tests

There are always a few risks when it comes to drawing blood, including:

• Infection
• Bruising
• Lightheadedness
• Soreness 

Be sure to let your healthcare provider know if you’re seeing swelling or redness, or feeling heat at the site of the blood draw, as those could be signs of infection.

BNP levels may also become elevated in a few other cases, which may sometimes indicate the presence of other conditions. These include:

• Chronic kidney disease (CKD)
• Hypertension (high blood pressure)
• Lung disease
• Overactive thyroid
• Advanced liver disease
• Elevated cortisol levels
• Brain hemorrhage 

BNP levels are also elevated when patients take Natrecor (nesiritide), a medication that treats heart failure. Further, increasing age, being female, and exercise in healthy individuals are also linked to higher levels.

However, because BNP elevations may be non-specific, a low BNP value is more helpful in ruling out heart failure than an elevated BNP level is helpful in diagnosing it. 

A Word From Verywell

Tests like BNP are part of the reason that healthcare providers are getting better and better at taking on heart failure. Highly accurate (98% of the time), normal BNP levels correctly rule out heart failure, and this test is easily applied and well-tolerated.

As knowledge about this hormone as well as its therapeutic potential grows, the outlook will continue to improve for cardiac disease patients. Clearly, BNP testing is another in an array of essential tools that have dramatically improved care and helped save lives.