Natriuretic peptides like ANP and BNP help regulate blood pressure, fluid balance, and heart strain. Learn how they work and what high levels mean.
Natriuretic peptide is a family of hormones your body makes to control fluid, sodium, and blood pressure. The three best-known members are atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Your heart releases ANP and BNP when its chambers stretch from extra fluid or pressure, and the kidneys respond by putting out more sodium and water.
Because BNP rises when the heart is under strain, natriuretic peptide blood tests are widely used to help diagnose and monitor heart failure. These same hormones are also the target of prescription heart failure medications.
What Does a Natriuretic Peptide Do?
Natriuretic peptides act as a natural counterweight to the systems that push blood pressure up. When the renin-angiotensin-aldosterone system tightens blood vessels and holds onto salt, natriuretic peptides push in the opposite direction.
Their main effects include:
- Natriuresis and diuresis: the kidneys excrete more sodium and water, which lowers blood volume.
- Vasodilation: blood vessels widen, reducing resistance to blood flow.
- Hormone suppression: renin, aldosterone, and antidiuretic hormone (ADH) all drop.
- Lower sympathetic activity: the nervous system signal that drives blood pressure upward is dampened.
- Cardiac protection: these hormones help limit fibrosis and fluid-driven stress on heart muscle.
The word "natriuretic" refers to sodium loss in urine, which is the signature effect these hormones were named for.
Atrial Natriuretic Peptide (ANP): The First One Discovered
ANP was identified in 1981, when researchers showed that injecting extracts of atrial tissue into rats triggered a rapid surge in urine output. Atrial natriuretic peptide (ANP) is stored in granules inside atrial muscle cells and released when the atria stretch.
ANP has a very short half-life of only a few minutes, so it acts quickly and then clears. Levels of the atrial natriuretic peptide hormone can rise briefly after a high-salt meal, during exercise, or with changes in posture. The ANP peptide is broken down in part by an enzyme called neprilysin, which has become an important drug target.
ANP, BNP, and CNP: How They Compare
All three peptides share the same basic goal of protecting the cardiovascular system, but they come from different places and serve different roles in testing and treatment.
| Peptide | Main Source | Primary Role | Clinical Use |
|---|---|---|---|
| ANP | Atrial muscle cells | Rapid sodium and water excretion, vasodilation | Research; informs drug design |
| BNP | Ventricles, mainly | Longer-acting fluid and pressure control | Blood test for heart failure evaluation |
| CNP | Blood vessel lining, brain, bone | Local vessel relaxation, bone growth signaling | Research; rare skeletal conditions |
Natriuretic Peptides as Heart Failure Biomarkers
BNP and NT-proBNP are among the most studied cardiac biomarkers in medicine. A BNP or NT-proBNP blood test is used to evaluate shortness of breath, leg swelling, and suspected heart failure in emergency rooms and clinics.
General interpretations look roughly like this, although ranges vary by lab and by age:
- BNP below 100 pg/mL — heart failure is unlikely as the cause of symptoms.
- BNP above 400 pg/mL — usually considered elevated and prompts further cardiac evaluation.
- NT-proBNP uses different cutoffs and rises naturally with older age and reduced kidney function.
BNP and NT-proBNP levels can also be elevated by conditions other than heart failure, including kidney disease, atrial fibrillation, sepsis, pulmonary embolism, and advanced age. A clinician interprets these numbers alongside symptoms, a physical exam, and imaging such as echocardiography.
What Raises or Lowers Natriuretic Peptide Levels
| Factor | Effect on ANP / BNP | Why |
|---|---|---|
| Heart failure | Raises | Stretched heart chambers release more peptide |
| Chronic kidney disease | Raises | Slower clearance from the blood |
| Older age | Raises | Especially true for NT-proBNP |
| Atrial fibrillation | Raises | Atrial stretch and altered filling |
| Obesity | Lowers | Lower baseline levels, which can mask risk |
| Successful diuresis | Lowers | Less fluid means less chamber stretch |
Occasional searches for an "anti natriuretic peptide" refer to experimental compounds that block natriuretic peptide receptors in laboratory models. No receptor-blocking natriuretic peptide drug is a standard clinical treatment today.
Drugs That Target the Natriuretic Peptide System
Two prescription approaches work directly on this hormone system, and both are given only under medical supervision.
- Sacubitril/valsartan (Entresto): pairs a neprilysin inhibitor with an angiotensin receptor blocker. Blocking neprilysin slows the breakdown of natriuretic peptides, so their effects last longer.
- Nesiritide (recombinant BNP): an intravenous form of BNP used in some hospital settings for acute decompensated heart failure.
These medicines are not a substitute for treating the underlying cause of heart strain, and they are not available as over-the-counter products.
Natriuretic Peptides vs. Consumer Peptide Products
Natriuretic peptides are hormones made inside your body. There is no pill or powder that raises ANP or BNP in a clinically meaningful way, and the word "peptide" on a label does not mean a product works on your heart.
Collagen peptide supplements, for example, are dietary proteins broken into short chains and marketed for joint and skin support. Products sold as a peptide for skin sit on the surface of the skin or in its upper layers, and they have nothing to do with sodium balance or blood pressure.
Research compounds get pulled into the same conversation. BPC-157 peptide for inflammation and wolverine peptide are sold online for laboratory use and are not FDA-approved for human use in the United States. Cosmetic formulas follow a similar pattern — the ordinary multi-peptide serum for hair density is a topical scalp product, not a hormone.
When to See a Healthcare Professional
Do not try to self-diagnose or self-treat based on a natriuretic peptide number. Seek medical care promptly for new shortness of breath, swelling in the legs or abdomen, rapid weight gain over a few days, chest pain, or fainting.
If you already have a BNP or NT-proBNP result, ask your clinician what it means in your specific situation. Reference ranges differ between laboratories, and the trend over time often matters more than any single value.
Frequently Asked Questions
What does a high natriuretic peptide level mean?
An elevated BNP or NT-proBNP usually means the heart is under strain, most often from heart failure. Levels can also rise with kidney disease, atrial fibrillation, older age, sepsis, or pulmonary embolism. A single result is always interpreted alongside symptoms, an exam, and imaging.
What is the difference between ANP and BNP?
Atrial natriuretic peptide (ANP) is stored in the atria and released quickly when they stretch, but it has a half-life of only a few minutes. BNP comes mainly from the ventricles, lasts longer in the bloodstream, and is the peptide most often measured with a blood test. Both promote sodium and water excretion and widen blood vessels.
Can you increase natriuretic peptide naturally?
You cannot meaningfully raise ANP or BNP with a supplement, because these are hormones your body produces and regulates on its own. Levels rise with heart strain, high sodium intake, exercise, and kidney problems, and they fall with obesity and after successful fluid removal. Prescription drugs such as sacubitril/valsartan extend the activity of these hormones under medical supervision.
This page provides educational research information and does not replace medical advice, diagnosis, or treatment.