BNP and NT-proBNP

Also Known As

Brain Natriuretic Peptide

proBNP

Natriuretic Peptides

Formal Name

B-type Natriuretic Peptide

N-terminal pro b-type Natriuretic Peptide

This article was last reviewed on

May 9, 2019.

This article waslast modified on July 29, 2020.

At a Glance

Why Get Tested?

To help detect, diagnose, and in some cases evaluate the severity of heart disease, including congestive heart failure (CHF)

When To Get Tested?

When you have symptoms such as shortness of breath, fatigue, excessive fluid in your abdomen, and swollen ankles and legs after a heart attack or during treatment for heart disease

Sample Required?

A blood sample drawn from a vein

Test Preparation Needed?

None

What is being tested?

B-type natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NTproBNP) are peptide (small proteins) that are either hormones or part of the peptide that contained the hormone at one time. They are continually produced in small quantities in the heart and released in larger quantities when the heart senses that it needs to work harder. This supports fluid retention and volume expansion in the arteries and veins. Subsequently, the heart muscle is stretched and works hard to pump blood under normal resting condition. Tests for BNP and NT-proBNP measure their levels in the blood in order to detect and evaluate heart failure. The two tests are not interchangeable and should not be used together. Your healthcare practitioner should order one or the other but not both.

It is important to note that heart failure is an incorrect term. The heart still pumps blood, it just has difficulty doing so. If your healthcare practitioners treat you for heart failure, they have several approaches depending upon the severity of the disease.

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 actually produced primarily by cells in the left ventricle of the heart. The left ventricle is the heart's main pumping chamber and is responsible for sending oxygenated blood from the lungs to the remainder of the body. It 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 split 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 having difficulty pumping sufficient amounts of blood to the body, the concentrations of BNP and NTproBNP produced can increase markedly. This may occur with many diseases that affect the heart and circulatory system. The increase in circulating BNP or NT-proBNP will reflect this diminished capacity to deliver oxygenated blood to the body.

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Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

Common Questions

How is the test used?

A test for BNP or NT-proBNP is primarily used to help detect, support diagnosis, and in some instances evaluate the severity of heart failure. The two tests are not interchangeable and should not be used together. Your healthcare practitioner should order one or the other but not both.

A BNP test or NT-proBNP test 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. Your healthcare practitioner may also prescribe a stress test, which takes place on a treadmill.

Heart failure can be confused with other conditions, and it may co-exist with them. BNP and NT-proBNP levels can help healthcare practitioners 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 who have had a heart attack may indicate an increased risk of further heart disease. Thus, a healthcare practitioner may use either BNP or NT-proBNP to evaluate risk of further heart disease in someone who has had a heart attack.
When is it ordered?
A BNP or NT-proBNP test may be ordered in a healthcare practitioner's office when you have 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 or in a hospital bed when you are in crisis and/or have symptoms that could be due to heart failure and healthcare practitioners need to quickly distinguish whether you are suffering from heart failure or some other medical problem.

Several BNP or NT-proBNP tests may be done over a period of time when you are being treated for heart failure to monitor the effects of therapy.
What does the test result mean?

Higher-than-normal results suggest that you have some degree of heart failure, and the level of BNP or NT-proBNP in the blood may be related to its severity. Higher levels of BNP or NT-proBNP are often associated with an increased need for aggressive therapy. In some individuals with chronic heart failure, the markers may remain elevated and cannot be used to monitor response.

Normal results indicate that signs and symptoms are likely due to something other than heart failure.
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 in the absence of disease.

Levels of NT-proBNP and BNP may be increased in persons with kidney disease due to reduced clearance. Obese individuals may have lower concentrations of BNP or NT-proBNP.

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.
How common is heart failure?

According to the American Heart Association, more than 6 million people in the United States are living with heart failure and the number is growing. It is estimated that one in five American adults age 40 and older will develop heart failure in their lifetime. You may be at increased risk of developing heart failure if you have conditions such as heart disease, high blood pressure, or diabetes, or if you have had a heart attack. Other risk factors include tobacco use, alcohol use, and obesity.
How is heart failure treated?

For information on treatment, read the article on Congestive Heart Failure or visit the American Heart Association webpage on Heart Failure.

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Related Images

Health Professionals – LOINC

LOINC Observation Identifiers Names and Codes (LOINC®) is the international standard for identifying health measurements, observations, and documents. It provides a common language to unambiguously identify things you can measure or observe that enables the exchange and aggregation of clinical results for care delivery, outcomes management, and research. Learn More.

Listed in the table below are the LOINC with links to the LOINC detail pages. Please note when you click on the hyperlinked code, you are leaving Lab Tests Online and accessing Loinc.org.

LOINC	LOINC Display Name
33762-6	Natriuretic peptide.B prohormone N-Terminal [Mass/Vol]
83107-3	Natriuretic peptide.B prohormone N-Terminal IA [Mass/Vol]
33763-4	Natriuretic peptide.B prohormone N-Terminal [Moles/Vol]
83108-1	Natriuretic peptide.B prohormone N-Terminal IA [Moles/Vol]
42637-9	Natriuretic peptide B (Bld) [Mass/Vol]
30934-4	Natriuretic peptide B [Mass/Vol]
47092-2	Natriuretic peptide B [Moles/Vol]

View Sources

Sources Used in Current Review

2019 Review completed by James G. Donnelly, PhD, DABCC, FCACB, Chief Scientific Officer and VP of Laboratory Operations, Babson Diagnostics.

(March 2, 2017) Wilson S Colucci, Horng H Chen. Natriuretic peptide measurement in heart failure. Up to Date. Available online at https://www.uptodate.com/contents/natriuretic-peptide-measurement-in-heart-failure. Accessed May 2019.

(December 20, 2017) Horng H Chen, Wilson S Colucci. Natriuretic peptide measurement in non-heart failure settings. Up to Date. Available online at https://www.uptodate.com/contents/natriuretic-peptide-measurement-in-non-heart-failure-settings. Accessed May 2019.

(Jan 10, 2018) Wilson S Colucci. Evaluation of the patient with suspected heart failure. Up to Date. Available online at https://www.uptodate.com/contents/evaluation-of-the-patient-with-suspected-heart-failure. Accessed May 2019.

(May 31, 2017) American Heart Association. Heart Failure. Available online at https://www.heart.org/en/health-topics/heart-failure/what-is-heart-failure. Accessed May 2019.

Sources Used in Previous Reviews

Interview with Alan H.B. Wu, PhD. Director, Clinical Chemistry, Hartford Hospital, Hartford, CT.

First Blood Test for Congestive Heart Failure Wins FDA Clearance. Clinical Laboratory Strategies, December 2000, Vol. 5, No. 12, Pg.1.

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Tang, W. (2004 February 27). NACB: Recommendations for the use of Cardiac Biomarkers in Heart Failure. NACB: Recommendations for the use of Cardiac Biomarkers in Heart Failure – Chapter 2 [Draft Guidelines]. Available online at http://www.nacb.org/lmpg/biomark/card_biomarkers_chp2.doc.

Bay, M. et. al. (2003). NT-proBNP: a new diagnostic screening tool to differentiate between patients with normal and reduced left ventricular systolic function. Heart ONLINE Heart 2003;89:150-154 [On-line journal]. Available online at http://heart.bmjjournals.com/cgi/content/full/89/2/150.

Diagnostic Products Corporation Acquires Nonexclusive Rights to a Key Cardiac Marker, NT-proBNP, from Roche Diagnostics—Agreement widens access to unique marker for heart failure and allows for better/earlier/improved therapy. (2004 February 11) DPC [On-line press release]. Available online at http://www.dpcweb.com/newsreleases/2004/february/ntprobnp.htm.

Roche Receives FDA Clearance for Elecsys proBNP Assay – First Automated Blood Test to Aid in the Diagnosis of Congestive Heart Failure (2002). Roche Diagnostics [On-line press release]. Available online at http://www.roche-diagnostics.com/press_lounge/press_releases/archive/2002_11_20.html.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006 Pp. 1630-1631.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC; Pg. 264.

deFilippi C. Natriuretic Peptides for Diagnosing Heart Failure and Beyond: What We Know in 2007. (May 24, 2007) Medscape Today. Available online at http://www.medscape.com/viewarticle/557030. Accessed September 2008.

Maher KO et al. B-type natriuretic peptide in the emergency diagnosis of critical heart disease in children. Pediatrics 2008 Jun; 121:e1484. Available online at http://pediatrics.aappublications.org/cgi/content/full/121/6/e1484?linkType=FULL&journalCode=pediatrics&resid=121/6/e1484. Accessed September 2008.

(Updated 2010 January 1). What is Heart Failure? National Heart Lung and Blood Institute [On-line information]. Available online at http://www.nhlbi.nih.gov/health/health-topics/topics/hf/. Accessed November 2011.

Lehman, C. et. al. (Revised 2011 March). Heart Failure. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/HeartFailure.html?client_ID=LTD. Accessed November 2011.

(© 1995-2011). Test ID: BNP83873 B-Type Natriuretic Peptide (BNP), Plasma. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/83873. Accessed November 2011.

(© 1995-2011). Test ID: PBNP84291 NT-Pro B-Type Natriuretic Peptide (BNP), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/84291. Accessed November 2011.

Malcolm, J. and Arnold, O. (Revised 2010 January) Heart Failure (HF) (Congestive Heart Failure). Merck Manual for Healthcare Professionals. [On-line information]. Available online at http://www.merckmanuals.com/professional/cardiovascular_disorders/heart_failure/heart_failure_hf.html?qt=BNP&alt=sh. Accessed November 2011.

Reviewer May 2015: Thomas Kampfrath, PhD, DABCC.

Lüers C, Schmidt A, Wachter R, Fritzsche F, Sutcliffe A, Kleta S, Zapf A, Hagenah G, Binder L, Maisch B, Pieske B. Serial NT-proBNP measurements for risk stratification of patients with decompensated heart failure. Herz. 2010 Oct;35(7):488-95.

William Clarke. Contemporary Practice in Clinical Chemistry, 2nd Edition Paperback – February 4, 2011. ISBN-13: 978-1594251023.

Michael L. Bishop, Edward P. Fody, Larry E. Schoeff. Clinical Chemistry: Principles, Techniques, and Correlations, 2013. 7th edition.

Kaplan & Pesce. Clinical Chemistry, 5th Edition. Theory, Analysis, Correlation. 2009.

(March 27, 2014) National Heart, Lung, Blood Institute. Who is at Risk of Heart Failure? Available online at http://www.nhlbi.nih.gov/health/health-topics/topics/hf/atrisk. Accessed May 2015.

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