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Natriuretic Peptide Tests (BNP, NT-proBNP)
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Natriuretic Peptide Tests (BNP, NT-proBNP)

Natriuretic peptide tests measure proteins released by the heart when it is under stress, helping providers diagnose or rule out heart failure.

What are natriuretic peptide tests?

These tests measure two proteins in the blood that the heart produces when it is working harder than normal to pump blood:

  • Brain natriuretic peptide (BNP): A hormone that helps reduce the heart's workload by signaling blood vessels to open wider and kidneys to remove excess water and salt.
  • N-terminal pro b-type natriuretic peptide (NT-proBNP): A protein that serves as an "ingredient" for making BNP.

What are they used for?

These tests are primarily used to diagnose or rule out heart failure in patients experiencing shortness of breath. For those already diagnosed with heart failure, the tests help assess the severity of the condition, predict worsening, or monitor the effectiveness of treatment.

Why do I need a natriuretic peptide test?

Your provider may order these tests if you have symptoms of heart failure, such as:

  • Shortness of breath
  • Swelling in the abdomen, feet, or legs
  • Fatigue or general weakness
  • Coughing
  • Difficulty sleeping while lying flat
  • Frequent urination, especially at night

What do the results mean?

  • Normal results: It is unlikely that you have heart failure. Your provider will investigate other causes for your symptoms. Note that obesity can sometimes lead to lower-than-expected levels.
  • Higher than normal levels: You may have heart failure. Your provider will likely order additional heart health tests to confirm the diagnosis.

Other conditions, such as kidney failure, heart valve disease, or lung disorders like pulmonary embolism, can also cause elevated levels of these proteins.

Frequently Asked Questions

Obesity, especially severe obesity, can suppress peptide levels, leading to a false‑low result. Atrial fibrillation and certain pulmonary conditions may also alter values. When a low result is seen in a high‑risk patient, clinicians often consider the clinical picture and may repeat the test or use imaging (e.g., echocardiogram) to avoid missing heart failure.
Typical cutoffs are <100 pg/mL for BNP and <300 pg/mL for NT‑proBNP in younger adults without renal disease. Levels rise with age and reduced kidney function; for patients over 75 years or with chronic kidney disease, higher thresholds (e.g., BNP <200 pg/mL, NT‑proBNP <900 pg/mL) may still be compatible with no heart failure. Your provider will interpret the result in the context of your age, renal function, and symptoms.
For stable chronic heart failure, many clinicians repeat the test every 3–6 months to track disease trajectory. If you experience worsening symptoms (increased shortness of breath, swelling, or weight gain), an earlier repeat is warranted to guide medication adjustments.
Most labs do not require fasting for BNP/NT‑proBNP, but you should inform the lab if you are on diuretics, ACE inhibitors, or ARBs, as these drugs can modestly lower the levels. If you are unsure, ask your provider whether to hold any heart‑failure medications for a few hours before the draw.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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