BNP test

What is BNP test

BNP test is a test for B-type natriuretic peptide (BNP or brain natriuretic peptide) and N-terminal pro b-type natriuretic peptide (NT-proBNP), which are substances that are produced in the heart and released when the heart is stretched and working hard to pump blood. Tests for BNP and NT-proBNP measure their levels in the blood in order to detect and evaluate congestive heart failure. BNP is stored in and secreted predominantly from membrane granules in the heart ventricles, and is continuously released from the heart in response to both ventricle volume expansion and pressure overload ¹.

BNP was initially called brain natriuretic peptide because it was first found in brain tissue (and to distinguish it from a similar protein made in the atria, or upper chambers, of the heart, termed ANP). BNP is a 32-amino acid-ringed peptide secreted by the heart to regulate blood pressure and fluid balance ². BNP is actually produced primarily by the left ventricle of the heart (the heart’s main pumping chamber). BNP is associated with blood volume and pressure and with the work that the heart must do in pumping blood throughout the body. Small amounts of a precursor protein, pro-BNP, are continuously produced by the heart. Pro-BNP is then cleaved by the enzyme called corin to release the active hormone BNP and an inactive fragment, NT-proBNP, into the blood.

When the left ventricle of the heart is stretched, the concentrations of BNP and NT-proBNP produced can increase markedly. This situation indicates that the heart is working harder and having more trouble meeting the body’s demands. This may occur with heart failure as well as with other diseases that affect the heart and circulatory system. Heart failure is a somewhat misleading term. It does not mean that the heart has stopped working; it just means that it is not pumping blood as effectively as it should be. The increase in circulating BNP or NT-proBNP will reflect this diminished capacity.

In general, BNP test results of less than 100 picograms/milliliter (pg/mL) are a sign a person does not have heart failure.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

Heart failure is a chronic, progressive condition in which the heart muscle is unable to pump enough blood to meet the body’s needs for blood and oxygen. Basically, the heart can’t keep up with its workload. Heart failure does not mean that your heart has stopped or is about to stop working. It means that your heart is not able to pump blood the way it should. It can affect one or both sides of the heart.

The weakening of the heart’s pumping ability causes:

Blood and fluid to back up into the lungs
The buildup of fluid in the feet, ankles and legs – called edema
Tiredness and shortness of breath

Common causes of heart failure are coronary artery disease, high blood pressure and diabetes. It is more common in people who are 65 years old or older, African Americans, people who are overweight, and people who have had a heart attack. Men have a higher rate of heart failure than women.

Your doctor will diagnose heart failure by doing a physical exam and heart tests. Treatment includes treating the underlying cause of your heart failure, medicines, and heart transplantation if other treatments fail.

How common is heart failure?

According to the National Heart, Lung and Blood Institute, about 5.7 million people in the United States are living with heart failure and the number is growing ³. People who are most at risk are those over 65 years old, African Americans, people who are overweight, those who have diabetes and people who have had a heart attack. Men are more likely than women to develop heart failure.

What is congestive heart failure?

Congestive heart failure (CHF), also called heart failure, is a condition in which the heart can no longer pump blood as efficiently as it used to. This causes blood and other fluids to back up in the body – particularly in the liver, lungs, hands, and feet.

The heart has two sides and four chambers. The right side of the heart receives oxygen-depleted blood from the body and sends it to the lungs. The left side of the heart receives oxygen-rich blood from the lungs and pumps it out to the body.

Heart failure can involve the heart’s left side, right side or both sides. However, it usually affects the left side first.

Congestive heart failure is a serious, progressive condition that is usually chronic and can be life-threatening. It may affect the right side, left side, or both sides of the heart. In people with congestive heart failure, reduced amounts of oxygen and nutrients are delivered to the body’s organs, which can cause damage and loss of function.

At first your heart tries to make up for this by:

Enlarging. The heart stretches to contract more strongly and keep up with the demand to pump more blood. Over time this causes the heart to become enlarged.
Developing more muscle mass. The increase in muscle mass occurs because the contracting cells of the heart get bigger. This lets the heart pump more strongly, at least initially.
Pumping faster. This helps increase the heart’s output.

The body also tries to compensate in other ways:

The blood vessels narrow to keep blood pressure up, trying to make up for the heart’s loss of power.
The body diverts blood away from less important tissues and organs (like the kidneys), the heart and brain.

These temporary measures mask the problem of heart failure, but they don’t solve it. Heart failure continues and worsens until these compensating processes no longer work.

Eventually the heart and body just can’t keep up, and the person experiences the fatigue, breathing problems or other symptoms that usually prompt a trip to the doctor.

The body’s compensation mechanisms help explain why some people may not become aware of their condition until years after their heart begins its decline. It’s also a good reason to have a regular checkup with your doctor.

There are a number of different causes for congestive heart failure. Most often, the heart has been damaged, either by high blood pressure (hypertension), previous heart attacks, or direct damage to the heart muscle (termed cardiomyopathy). Congestive heart failure can also occur when there is damage to the valves within the heart or with scarring in the pericardium, the membrane surrounding the heart. Rarely, congestive heart failure occurs when the heart is forced to beat more forcefully than normal, as in severe hyperthyroidism, and cannot keep up with the demand. The risk of congestive heart failure is increased in those who are overweight, have diabetes, smoke, or who abuse alcohol or cocaine.

Congestive heart failure is common in the elderly as the heart becomes less efficient with age. The National Heart, Lung and Blood Institute estimates that about 5.7 million people in the United States have heart failure. For people over the age of 65, it is one of the most common causes of hospitalization.

Congestive heart failure signs and symptoms

If blood backs up from the right side of the heart, symptoms of heart failure typically start with swelling of the legs and ankles that gets worse when the person stands and improves when the person lies down. If blood backs up from the left side of the heart into the lungs, it can cause shortness of breath and coughing, especially during exercise (such as walking up stairs) or when lying down flat in bed. Many people with heart failure have symptoms related to blood backing up on both the right and left sides of the heart.

In addition to swelling (edema) and shortness of breath, symptoms can include:

Heart palpitation or rapid pulse
Weakness and fatigue
Decreased stamina, inability or reduced ability to perform physical exercise
Coughing or wheezing
Sudden weight gain
Loss of appetite
Nausea

Congestive heart failure causes

Conditions that damage or overwork the heart muscle can cause heart failure. Over time, the heart weakens. It isn’t able to fill with and/or pump blood as well as it should. As the heart weakens, certain proteins and substances might be released into the blood. These substances have a toxic effect on the heart and blood flow, and they worsen heart failure.

Causes of heart failure include:

Coronary heart disease
Diabetes
High blood pressure
Other heart conditions or diseases
Other factors

Coronary Heart Disease

Coronary heart disease is a condition in which a waxy substance called plaque builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart muscle.

Plaque narrows the arteries and reduces blood flow to your heart muscle. The buildup of plaque also makes it more likely that blood clots will form in your arteries. Blood clots can partially or completely block blood flow. Coronary heart disease can lead to chest pain or discomfort called angina, a heart attack, and heart damage.

Diabetes

Diabetes is a disease in which the body’s blood glucose (sugar) level is too high. The body normally breaks down food into glucose and then carries it to cells throughout the body. The cells use a hormone called insulin to turn the glucose into energy.

In diabetes, the body doesn’t make enough insulin or doesn’t use its insulin properly. Over time, high blood sugar levels can damage and weaken the heart muscle and the blood vessels around the heart, leading to heart failure.

High Blood Pressure

Blood pressure is the force of blood pushing against the walls of the arteries. If this pressure rises and stays high over time, it can weaken your heart and lead to plaque buildup.

Blood pressure is considered high if it stays at or above 140/90 mmHg over time. (The mmHg is millimeters of mercury—the units used to measure blood pressure.) If you have diabetes or chronic kidney disease, high blood pressure is defined as 130/80 mmHg or higher.

Other Heart Conditions or Diseases

Other conditions and diseases also can lead to heart failure, such as:

Arrhythmia. Happens when a problem occurs with the rate or rhythm of the heartbeat.
Cardiomyopathy. Happens when the heart muscle becomes enlarged, thick, or rigid.
Congenital heart defects. Problems with the heart’s structure are present at birth.
Heart valve disease. Occurs if one or more of your heart valves doesn’t work properly, which can be present at birth or caused by infection, other heart conditions, and age.

Other Factors

Other factors also can injure the heart muscle and lead to heart failure. Examples include:

Alcohol abuse or cocaine and other illegal drug use
HIV/AIDS
Thyroid disorders (having either too much or too little thyroid hormone in the body)
Too much vitamin E
Treatments for cancer, such as radiation and chemotherapy

Heart failure risk factors

Heart failure is more common in:

People who are age 65 or older. Aging can weaken the heart muscle. Older people also may have had diseases for many years that led to heart failure. Heart failure is a leading cause of hospital stays among people on Medicare.
Blacks are more likely to have heart failure than people of other races. They’re also more likely to have symptoms at a younger age, have more hospital visits due to heart failure, and die from heart failure.
People who are overweight. Excess weight puts strain on the heart. Being overweight also increases your risk of heart disease and type 2 diabetes. These diseases can lead to heart failure.
People who have had a heart attack. Damage to the heart muscle from a heart attack and can weaken the heart muscle.

Children who have congenital heart defects also can develop heart failure. These defects occur if the heart, heart valves, or blood vessels near the heart don’t form correctly while a baby is in the womb. Congenital heart defects can make the heart work harder. This weakens the heart muscle, which can lead to heart failure. Children don’t have the same symptoms of heart failure or get the same treatments as adults. This Health Topic focuses on heart failure in adults.

Congestive heart failure prevention

You can take steps to prevent heart failure. The sooner you start, the better your chances of preventing or delaying the condition.

For People Who Have Healthy Hearts

If you have a healthy heart, you can take action to prevent heart disease and heart failure. To reduce your risk of heart disease:

Avoid using illegal drugs.
Adopt heart-healthy lifestyle habits.

For People Who Are at High Risk for Heart Failure

Even if you’re at high risk for heart failure, you can take steps to reduce your risk. People at high risk include those who have coronary heart disease, high blood pressure, or diabetes.

Talk with your doctor about what types and amounts of physical activity are safe for you.
Treat and control any conditions that can cause heart failure. Take medicines as your doctor prescribes.
Avoid drinking alcohol.
See your doctor for ongoing care.

For People Who Have Heart Damage but No Signs of Heart Failure

If you have heart damage but no signs of heart failure, you can still reduce your risk of developing the condition. In addition to the steps above, take your medicines as prescribed to reduce your heart’s workload.

Congestive heart failure diagnosis

Your doctor will diagnose heart failure based on your medical and family histories, a physical exam, and test results. The signs and symptoms of heart failure also are common in other conditions. Thus, your doctor will:

Find out whether you have a disease or condition that can cause heart failure, such as coronary heart disease (CHD), high blood pressure, or diabetes
Rule out other causes of your symptoms
Find any damage to your heart and check how well your heart pumps blood

Early diagnosis and treatment can help people who have heart failure live longer, more active lives.

Medical and Family Histories

Your doctor will ask whether you or others in your family have or have had a disease or condition that can cause heart failure.

Your doctor also will ask about your symptoms. He or she will want to know which symptoms you have, when they occur, how long you’ve had them, and how severe they are. Your answers will help show whether and how much your symptoms limit your daily routine.

Physical Exam

During the physical exam, your doctor will:

Listen to your heart for sounds that aren’t normal
Listen to your lungs for the sounds of extra fluid buildup
Look for swelling in your ankles, feet, legs, abdomen, and the veins in your neck

Diagnostic Tests

No single test can diagnose heart failure. If you have signs and symptoms of heart failure, your doctor may recommend one or more tests.

Your doctor also may refer you to a cardiologist. A cardiologist is a doctor who specializes in diagnosing and treating heart diseases and conditions.

EKG (Electrocardiogram)

An EKG is a simple, painless test that detects and records the heart’s electrical activity. The test shows how fast your heart is beating and its rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through your heart.

An EKG may show whether the walls in your heart’s pumping chambers are thicker than normal. Thicker walls can make it harder for your heart to pump blood. An EKG also can show signs of a previous or current heart attack.

Chest X Ray

A chest x ray takes pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. This test can show whether your heart is enlarged, you have fluid in your lungs, or you have lung disease.

BNP Blood Test

This test checks the level of BNP. The level of BNP hormone rises during heart failure.

Echocardiography

Echocardiography (echo) uses sound waves to create a moving picture of your heart. The test shows the size and shape of your heart and how well your heart chambers and valves work.

Echo also can identify areas of poor blood flow to the heart, areas of heart muscle that aren’t contracting normally, and heart muscle damage caused by lack of blood flow.

Echo might be done before and after a stress test (see below). A stress echo can show how well blood is flowing through your heart. The test also can show how well your heart pumps blood when it beats.

Doppler Ultrasound

A Doppler ultrasound uses sound waves to measure the speed and direction of blood flow. This test often is done with echo to give a more complete picture of blood flow to the heart and lungs.

Doctors often use Doppler ultrasound to help diagnose right-side heart failure.

Holter Monitor

A Holter monitor records your heart’s electrical activity for a full 24- or 48-hour period, while you go about your normal daily routine.

You wear small patches called electrodes on your chest. Wires connect the patches to a small, portable recorder. The recorder can be clipped to a belt, kept in a pocket, or hung around your neck.

Nuclear Heart Scan

A nuclear heart scan shows how well blood is flowing through your heart and how much blood is reaching your heart muscle.

During a nuclear heart scan, a safe, radioactive substance called a tracer is injected into your bloodstream through a vein. The tracer travels to your heart and releases energy. Special cameras outside of your body detect the energy and use it to create pictures of your heart.

A nuclear heart scan can show where the heart muscle is healthy and where it’s damaged.

A positron emission tomography (PET) scan is a type of nuclear heart scan. It shows the level of chemical activity in areas of your heart. This test can help your doctor see whether enough blood is flowing to these areas. A PET scan can show blood flow problems that other tests might not detect.

Cardiac Catheterization

During cardiac catheterization, a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck and threaded to your heart. This allows your doctor to look inside your coronary (heart) arteries.

During this procedure, your doctor can check the pressure and blood flow in your heart chambers, collect blood samples, and use x rays to look at your coronary arteries.

Coronary Angiography

Coronary angiography usually is done with cardiac catheterization. A dye that can be seen on x ray is injected into your bloodstream through the tip of the catheter.

The dye allows your doctor to see the flow of blood to your heart muscle. Angiography also shows how well your heart is pumping.

Stress Test

Some heart problems are easier to diagnose when your heart is working hard and beating fast. During stress testing, you exercise to make your heart work hard and beat fast.

You may walk or run on a treadmill or pedal a bicycle. If you can’t exercise, you may be given medicine to raise your heart rate.

Heart tests, such as nuclear heart scanning and echo, often are done during stress testing.

Cardiac MRI

Cardiac MRI (magnetic resonance imaging) uses radio waves, magnets, and a computer to create pictures of your heart as it’s beating. The test produces both still and moving pictures of your heart and major blood vessels.

A cardiac MRI can show whether parts of your heart are damaged. Doctors also have used MRI in research studies to find early signs of heart failure, even before symptoms appear.

Thyroid Function Tests

Thyroid function tests show how well your thyroid gland is working. These tests include blood tests, imaging tests, and tests to stimulate the thyroid. Having too much or too little thyroid hormone in the blood can lead to heart failure.

Congestive heart failure treatment

Early diagnosis and treatment can help people who have heart failure live longer, more active lives. Treatment for heart failure depends on the type and severity of the heart failure.

The goals of treatment for all stages of heart failure include:

Treating the condition’s underlying cause, such as coronary heart disease, high blood pressure, or diabetes
Reducing symptoms
Stopping the heart failure from getting worse
Increasing your lifespan and improving your quality of life

Treatments usually include heart-healthy lifestyle changes, medicines, and ongoing care. If you have severe heart failure, you also may need medical procedures or surgery.

Heart-Healthy Lifestyle Changes

Your doctor may recommend heart-healthy lifestyle changes if you have heart failure. Heart-healthy lifestyle changes include:

Heart-healthy eating
Aiming for a healthy weight
Physical activity
Quitting smoking

Medicines

Your doctor will prescribe medicines based on the type of heart failure you have, how severe it is, and your response to certain medicines. The following medicines are commonly used to treat heart failure:

ACE (angiontensin converting enzyme) inhibitors lower blood pressure and reduce strain on your heart. They also may reduce the risk of a future heart attack.
Aldosterone antagonists trigger the body to remove excess sodium through urine. This lowers the volume of blood that the heart must pump.
Angiotensin receptor blockers relax your blood vessels and lower blood pressure to decrease your heart’s workload.
Beta blockers slow your heart rate and lower your blood pressure to decrease your heart’s workload.
Digoxin makes the heart beat stronger and pump more blood.
Diuretics (fluid pills) help reduce fluid buildup in your lungs and swelling in your feet and ankles.
Isosorbide dinitrate/hydralazine hydrochloride helps relax your blood vessels so your heart doesn’t work as hard to pump blood. Studies have shown that this medicine can reduce the risk of death in blacks. More studies are needed to find out whether this medicine will benefit other racial groups.

Take all medicines regularly, as your doctor prescribes. Don’t change the amount of your medicine or skip a dose unless your doctor tells you to. You should still follow a heart healthy lifestyle, even if you take medicines to treat your heart failure.

Ongoing Care

You should watch for signs that heart failure is getting worse. For example, weight gain may mean that fluids are building up in your body. Ask your doctor how often you should check your weight and when to report weight changes.

Getting medical care for other related conditions is important. If you have diabetes or high blood pressure, work with your health care team to control these conditions. Have your blood sugar level and blood pressure checked. Talk with your doctor about when you should have tests and how often to take measurements at home.

Try to avoid respiratory infections like the flu and pneumonia. Talk with your doctor or nurse about getting flu and pneumonia vaccines.

Many people who have severe heart failure may need treatment in a hospital from time to time. Your doctor may recommend oxygen therapy, which can be given in a hospital or at home.

Take Steps To Prevent Heart Failure From Getting Worse

Certain actions can worsen your heart failure, such as:

Forgetting to take your medicines
Not following your diet (for example, eating salty foods)
Drinking alcohol

These actions can lead to a hospital stay. If you have trouble following your diet, talk with your doctor. He or she can help arrange for a dietitian to work with you. Avoid drinking alcohol.

People who have heart failure often have other serious conditions that require ongoing treatment. If you have other serious conditions, you’re likely taking medicines for them as well as for heart failure.

Taking more than one medicine raises the risk of side effects and other problems. Make sure your doctors and your pharmacist have a complete list of all of the medicines and over-the-counter products that you’re taking.

Tell your doctor right away about any problems with your medicines. Also, talk with your doctor before taking any new medicine prescribed by another doctor or any new over-the-counter medicines or herbal supplements.

Try to avoid respiratory infections like the flu and pneumonia. Ask your doctor or nurse about getting flu and pneumonia vaccines.

Medical Procedures and Surgery

As heart failure worsens, lifestyle changes and medicines may no longer control your symptoms. You may need a medical procedure or surgery.

In heart failure, the right and left sides of the heart may no longer contract at the same time. This disrupts the heart’s pumping. To correct this problem, your doctor might implant a cardiac resynchronization therapy device (a type of pacemaker) near your heart. This device helps both sides of your heart contract at the same time, which can decrease heart failure symptoms.

Some people who have heart failure have very rapid, irregular heartbeats. Without treatment, these heartbeats can cause sudden cardiac arrest. Your doctor might implant an implantable cardioverter defibrillator near your heart to solve this problem. An implantable cardioverter defibrillator checks your heart rate and uses electrical pulses to correct irregular heart rhythms.

People who have severe heart failure symptoms at rest, despite other treatments, may need:

A mechanical heart pump, such as a left ventricular assist device. This device helps pump blood from the heart to the rest of the body. You may use a heart pump until you have surgery or as a long-term treatment.
Heart transplant. A heart transplant is an operation in which a person’s diseased heart is replaced with a healthy heart from a deceased donor. Heart transplants are done as a life-saving measure for end-stage heart failure when medical treatment and less drastic surgery have failed.

How is BNP blood test used?

A test for B-type natriuretic peptide (BNP) or N-terminal pro b-type natriuretic peptide (NT-proBNP) is primarily used to help detect, diagnose, and evaluate the severity of heart failure. It can be used, along with other cardiac biomarker tests, to detect heart stress and damage and/or along with lung function tests to distinguish between causes of shortness of breath. Chest X-rays and an ultrasound test called echocardiography may also be performed.

Heart failure can be confused with other conditions, and it may co-exist with them. BNP and NT-proBNP levels can help doctors differentiate between heart failure and other problems, such as lung disease. An accurate diagnosis is important because the treatments are often different and must be started as soon as possible.

Although BNP and NT-proBNP are usually used to recognize heart failure, an increased level in people with acute coronary syndrome indicates an increased risk of recurrent events. Acute coronary syndrome is a term for any condition that suddenly stops (or severely reduces) blood from flowing to the heart. When blood cannot flow to the heart, the heart muscle can become damaged. Heart attack and unstable angina are both acute coronary syndromes. Thus, a health practitioner may use either BNP or NT-proBNP to evaluate risk of a future cardiac event in someone with acute coronary syndrome.

When is BNP blood test ordered?

A BNP or NT-proBNP test may be ordered in a doctor’s office when a person has signs and symptoms that could be due to heart failure. These may include:

Difficulty breathing, shortness of breath
Fatigue
Swelling in the feet, ankles, legs, abdomen

Testing may be done in the emergency room when someone is in crisis and/or has symptoms that could be due to heart failure and health practitioners need to quickly determine if a person is suffering from heart failure or some other medical problem.

Several BNP or NT-proBNP tests may be done over a period of time when an individual is being treated for heart failure to monitor the effects of therapy.

BNP blood test normal range

Males BNP test normal range

Age < or =45 years: < or =35 pg/mL
Age 46 years: < or =36 pg/mL
Age 47 years: < or =37 pg/mL
Age 48 years: < or =38 pg/mL
Age 49 years: < or =39 pg/mL
Age 50 years: < or =40 pg/mL
Age 51 years: < or =41 pg/mL
Age 52 years: < or =42 pg/mL
Age 53 years: < or =43 pg/mL
Age 54 years: < or =45 pg/mL
Age 55 years: < or =46 pg/mL
Age 56 years: < or =47 pg/mL
Age 57 years: < or =48 pg/mL
Age 58 years: < or =49 pg/mL
Age 59 years: < or =51 pg/mL
Age 60 years: < or =52 pg/mL
Age 61 years: < or =53 pg/mL
Age 62 years: < or =55 pg/mL
Age 63 years: < or =56 pg/mL
Age 64 years: < or =57 pg/mL
Age 65 years: < or =59 pg/mL
Age 66 years: < or =60 pg/mL
Age 67 years: < or =62 pg/mL
Age 68 years: < or =64 pg/mL
Age 69 years: < or =65 pg/mL
Age 70 years: < or =67 pg/mL
Age 71 years: < or =69 pg/mL
Age 72 years: < or =70 pg/mL
Age 73 years: < or =72 pg/mL
Age 74 years: < or =74 pg/mL
Age 75 years: < or =76 pg/mL
Age 76 years: < or =78 pg/mL
Age 77 years: < or =80 pg/mL
Age 78 years: < or =82 pg/mL
Age 79 years: < or =84 pg/mL
Age 80 years: < or =86 pg/mL
Age 81 years: < or =88 pg/mL
Age 82 years: < or =91 pg/mL
Age > or =83 years: < or =93 pg/mL

Females BNP test normal range

Age < or =45 years: < or =64 pg/mL
Age 46 years: < or =66 pg/mL
Age 47 years: < or =67 pg/mL
Age 48 years: < or =69 pg/mL
Age 49 years: < or =71 pg/mL
Age 50 years: < or =73 pg/mL
Age 51 years: < or =74 pg/mL
Age 52 years: < or =76 pg/mL
Age 53 years: < or =78 pg/mL
Age 54 years: < or =80 pg/mL
Age 55 years: < or =82 pg/mL
Age 56 years: < or =84 pg/mL
Age 57 years: < or =87 pg/mL
Age 58 years: < or =89 pg/mL
Age 59 years: < or =91 pg/mL
Age 60 years: < or =93 pg/mL
Age 61 years: < or =96 pg/mL
Age 62 years: < or =98 pg/mL
Age 63 years: < or =101 pg/mL
Age 64 years: < or =103 pg/mL
Age 65 years: < or =106 pg/mL
Age 66 years: < or =109 pg/mL
Age 67 years: < or =112 pg/mL
Age 68 years: < or =114 pg/mL
Age 69 years: < or =117 pg/mL
Age 70 years: < or =120 pg/mL
Age 71 years: < or =123 pg/mL
Age 72 years: < or =127 pg/mL
Age 73 years: < or =130 pg/mL
Age 74 years: < or =133 pg/mL
Age 75 years: < or =137 pg/mL
Age 76 years: < or =140 pg/mL
Age 77 years: < or =144 pg/mL
Age 78 years: < or =147 pg/mL
Age 79 years: < or =151 pg/mL
Age 80 years: < or =155 pg/mL
Age 81 years: < or =159 pg/mL
Age 82 years: < or =163 pg/mL
Age > or =83 years: < or =167 pg/mL

What does abnormal BNP blood test result mean?

Higher-than-normal results suggest that a person has some degree of heart failure, and the level of BNP or NT-proBNP in the blood is related to its severity. Higher levels of BNP or NT-proBNP are often associated with a worse outlook (prognosis) for the person.

Normal results indicate that the person’s symptoms are likely due to something other than heart failure.

BNP level >normal <200 pg/mL: likely compensated congestive heart failure
BNP level > or =200 to < or =400 pg/mL: likely moderate congestive heart failure
BNP level >400 pg/mL: likely moderate-to-severe congestive heart failure

Elevation in BNP can occur due to right heart failure with cor pulmonale (200-500 pg/mL), pulmonary hypertension (300-500 pg/mL), and acute pulmonary embolism (150-500 pg/mL). Elevations also occur in patients with acute coronary syndromes.

Lack of elevations have been reported if congestive heart failure is very acute (first hour) or with ventricular inflow obstruction (hypertrophic obstructive cardiomyopathy, mitral stenosis, atrial myxoma).

Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedures, may have circulating antianimal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.

Doctors usually classify patients’ heart failure according to the severity of their symptoms. The table below describes the most commonly used classification system, the New York Heart Association (NYHA) Functional Classification ⁴. It places patients in one of four categories based on how much they are limited during physical activity.

Table 1. New York Heart Association Classes of Heart Failure

Class	Patient Symptoms
I	No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea (shortness of breath).
II	Slight limitation of physical activity. Comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea (shortness of breath).
III	Marked limitation of physical activity. Comfortable at rest. Less than ordinary activity causes fatigue, palpitation, or dyspnea.
IV	Unable to carry on any physical activity without discomfort. Symptoms of heart failure at rest. If any physical activity is undertaken, discomfort increases.

Class	Objective Assessment
A	No objective evidence of cardiovascular disease. No symptoms and no limitation in ordinary physical activity.
B	Objective evidence of minimal cardiovascular disease. Mild symptoms and slight limitation during ordinary activity. Comfortable at rest.
C	Objective evidence of moderately severe cardiovascular disease. Marked limitation in activity due to symptoms, even during less-than-ordinary activity. Comfortable only at rest.
D	Objective evidence of severe cardiovascular disease. Severe limitations. Experiences symptoms even while at rest.

For Example:

A patient with minimal or no symptoms but a large pressure gradient across the aortic valve or severe obstruction of the left main coronary artery is classified: Function Capacity I, Objective Assessment D
A patient with severe anginal syndrome but angiographically normal coronary arteries is classified: Functional Capacity IV, Objective Assessment A

[Source ⁴ ]

Brain natriuretic peptide (BNP) levels are loosely correlated with New York Heart Association (NYHA) functional class (see Table 2).

Table 2. BNP Interpretive Levels for Heart Failure

New York Heart Association Functional Class	5th to 95th Percentile	Median
I	15 to 499 pg/mL	95 pg/mL
II	10 to 1,080 pg/mL	222 pg/mL
III	38 to >1,300 pg/mL	459 pg/mL
IV	147 to >1,300 pg/mL	1,006 pg/mL
All heart failure	22 to >1,300 pg/mL	360 pg/mL

[Source ⁵ ]

Is there anything else I should know?

BNP and NT-proBNP levels decrease in most people who are taking drug therapies for heart failure, such as angiotensin-converting enzyme (ACE) inhibitors, beta blockers, and diuretics.

Levels of both BNP and NT-proBNP tend to increase with age.

Levels of NT-proBNP and BNP may be increased in persons with kidney disease due to reduced clearance.

While both BNP and NT-proBNP will rise with left ventricle dysfunction and either can be measured for diagnosis or monitoring therapy, they are not interchangeable and the results cannot be directly compared.

McNairy M, Gardetto N, Clopton P, et al: Stability of B-type natriuretic peptide levels during exercise in patients with congestive heart failure: implications for outpatient monitoring with B-type natriuretic peptide. Am Heart J 2002 March;143(3):406-411[↩]
Krishnaswamy P, Lubien E, Clopton P, et al: Utility of B-natriuretic peptide as a rapid, point-of-care test for screening patients undergoing echocardiography to determine left ventricular dysfunction. Am J Med 2001;111(4):274-279[↩]
Heart Failure. https://www.nhlbi.nih.gov/health-topics/heart-failure[↩]
Dolgin M, Association NYH, Fox AC, Gorlin R, Levin RI, New York Heart Association. Criteria Committee. Nomenclature and criteria for diagnosis of diseases of the heart and great vessels. 9th ed. Boston, MA: Lippincott Williams and Wilkins; March 1, 1994.[↩][↩]
https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/83873[↩]