Measurement of natriuretic peptide levels released from the ventricles in a blood sample; used in the diagnosis, severity assessment, and follow-up of heart failure.
Indication
- Unexplained shortness of breath, rapid fatigue, or decreased exercise capacity
- Leg swelling (edema), abdominal swelling, or nighttime shortness of breath
- Suspicion of fluid in the lungs (pulmonary edema)
- Assessment of the severity of known heart failure
- Monitoring of treatment response and medication titration
- Differentiation between cardiac and pulmonary causes in patients presenting with acute shortness of breath
- Screening of patients at high risk for heart failure (diabetes, hypertension)
Preparation
- No special fasting required
- Current heart failure medications (diuretics, ACE-i, ARB, ARNI, beta blockers) should be reported
- Recent exercise or symptom status should be communicated to the physician
How it's performed
- The patient is prepared in a sitting or lying position
- A 5 mL blood sample is taken via vein from the arm
- BNP or NT-proBNP level is measured by automated immunoassay
- Results are evaluated together with the patient's age, kidney function, and clinical status
- Results are usually reported within 30-60 minutes
Post-procedure
- BNP <100 pg/mL or NT-proBNP <300 pg/mL largely rules out acute heart failure
- Age-based NT-proBNP thresholds: above 450 pg/mL for <50 years, 900 pg/mL for 50-75 years, and 1800 pg/mL for >75 years support diagnosis
- ECG, echocardiography, and cardiology consultation are planned for elevated values
- Response is reassessed by repeat measurement every 1-3 months after starting treatment
- Interpretation of values differs in dialysis patients and atrial fibrillation
Risks
- Pain, bruising, or hematoma at the blood draw site
- Rare fainting (vasovagal reaction)
- Difficulty interpreting borderline values in the elderly, in renal failure, or in atrial fibrillation
- Values may appear lower than actual in obese individuals
- In patients on ARNI (sacubitril/valsartan) therapy, BNP is elevated, while NT-proBNP provides accurate assessment
FAQ
What is the difference between BNP and NT-proBNP?
Both are fragments of the same prohormone. NT-proBNP has a longer half-life and provides more reliable results, especially in patients on ARNI therapy. The choice of test depends on laboratory availability.
Does a low BNP/NT-proBNP definitively rule out heart failure?
Low values largely rule out acute heart failure; however, the final diagnosis is made together with clinical findings and echocardiography.
Do I need to fast for the test?
No, fasting is not required. The test can be done at any time of day.
How often should the results be repeated?
It is repeated every 1-3 months in patients whose treatment is being started or changed, and annually in stable patients, according to physician recommendation.
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