A brain natriuretic peptide (BNP) test measures the amount of the BNP hormone in your blood. BNP is made by your heart and indicates how well your heart is working. Normally, only a low amount of BNP is found in your blood. However, if your heart has to work harder than usual over a long period of time, such as from heart failure, the heart releases more BNP, increasing the blood level of BNP. The BNP level will drop when treatment for heart failure is working.

Why It Is Done

The brain natriuretic peptide (BNP) test is used to:

• Check for heart failure. A doctor may think you have heart failure if you are having problems such as difficulty breathing and swelling (edema) in the arms or legs.
• Find out how severe heart failure is.
• Check the response of treatment for heart failure.

How To Prepare

You may be asked to not eat or drink anything except water for 8 to 12 hours before having a BNP test.

Talk to your health professional about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will indicate. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

The health professional drawing your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Apply a gauze pad or cotton ball over the needle site as the needle is removed.
• Apply pressure to the site and then a bandage.

How It Feels

You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. However, many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.

Risks

There is very little risk of complications from having blood drawn from a vein.

• You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.
• Rarely, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated with a warm compress applied several times daily.
• Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning drugs, tell your health professional before your blood is drawn.