Brain natriuretic peptide
In medicine, brain natriuretic peptide (BNP), also called B-Type natriuretic peptide, is a "peptide that is secreted by the brain and the heart atria, stored mainly in cardiac ventricular myocardium. It can cause natriuresis; diuresis; vasodilation; and inhibits secretion of renin and aldosterone. It improves heart function. It contains 32 amino acids."
BNP is one member or a family of closely related peptides called "natriuretic peptides" because of their ability to stimulate sodium excretion (natriuresis). Natriuretic peptides are functional antagonists to the renin-angiotensin-aldosterone system. BNP was given its name because it was first discovered in the porcine brain.  However, confusingly, there appears to be relatively little BNP expressed in the brain compared to atrial natriuretic peptide  A related peptide is N-terminal pro-B-type natriuretic peptide.
BNP test accuracy
|BNP > 100 pg per milliliter||90%||76%|
|BNP > 50 pg per milliliter||97%||62%|
The optimal level to exclude heart failure may depend on the clinical setting.
Effect on clinical decision making
Evaluation and management of acute dyspnea
Monitoring of chronic heart failure
Treating heart failure based on BNP might improve care according to a meta-analysis. In one trail included in the meta-analysis, there was no improvement by treating for a goal of brain natriuretic peptide less than 400 pg/mL in patients younger than 75 years and less than 800 pg/mL in patients aged 75 years or older. A second trial found uncertain benefit from targeting NT-proBNP level < 150 pmol/l.
Treatment with nesiritide
Nesiritide is considered adjunctive therapy for patients in severe heart failure, principally as a vasodilator, when neither nitroglycerine nor sodium nitroprusside provide sufficient benefit. Small studies suggest it may increase the risk of death, and further trials are underway. It has been suggested that intermittent intravenous infusion, as opposed to continuous microdrip administration, worsens the hazard. 
Clinical practice guidelines
- "Measurement of natriuretic peptides (BNP and NT-proBNP) can be useful in the evaluation of patients presenting in the urgent care setting in whom the clinical diagnosis of HF is uncertain. Measurement of natriuretic peptides (BNP and NT-proBNP) can be helpful in risk stratification."
- "The value of serial measurements of BNP to guide therapy for patients with HF is not well established."
- Anonymous (2015), Brain natriuretic peptide (English). Medical Subject Headings. U.S. National Library of Medicine.
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- Maisel AS, Krishnaswamy P, Nowak RM, et al (July 2002). "Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure". N Engl J Med 347: 161–7. DOI:10.1056/NEJMoa020233. PMID 12124404. Research Blogging.
- Rogers RK, Stoddard GJ, Greene T, Michaels AD, Fernandez G, Freeman A et al. (2009). "Usefulness of adjusting for clinical covariates to improve the ability of B-type natriuretic peptide to distinguish cardiac from noncardiac dyspnea.". Am J Cardiol 104 (5): 689-94. DOI:10.1016/j.amjcard.2009.04.043. PMID 19699346. Research Blogging.
- Schneider HG, Lam L, Lokuge A, et al. (March 2009). "B-type natriuretic peptide testing, clinical outcomes, and health services use in emergency department patients with dyspnea: a randomized trial". Ann. Intern. Med. 150 (6): 365–71. PMID 19293069.
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- Porapakkham P, Porapakkham P, Zimmet H, Billah B, Krum H (2010). "B-Type Natriuretic Peptide-Guided Heart Failure Therapy: A Meta-analysis.". Arch Intern Med 170 (6): 507-14. DOI:10.1001/archinternmed.2010.35. PMID 20308637. Research Blogging.
- Pfisterer M, Buser P, Rickli H, et al (January 2009). "BNP-guided vs symptom-guided heart failure therapy: the Trial of Intensified vs Standard Medical Therapy in Elderly Patients With Congestive Heart Failure (TIME-CHF) randomized trial". JAMA 301 (4): 383–92. DOI:10.1001/jama.2009.2. PMID 19176440. Research Blogging.
- Lainchbury JG, Troughton RW, Strangman KM, Frampton CM, Pilbrow A, Yandle TG et al. (2009). "N-terminal pro-B-type natriuretic peptide-guided treatment for chronic heart failure: results from the BATTLESCARRED (NT-proBNP-Assisted Treatment To Lessen Serial Cardiac Readmissions and Death) trial.". J Am Coll Cardiol 55 (1): 53-60. DOI:10.1016/j.jacc.2009.02.095. PMID 20117364. Research Blogging.
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- Natrecor IV, American Society of Health-System Pharmacists
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