From the Guidelines
Normal BNP levels are defined as BNP levels <100 ng/L or NT-proBNP levels <400 ng/L. According to the most recent and highest quality study available, 1, BNP is a hormone released by the heart when it's under stress, particularly when the heart is having difficulty pumping blood effectively. Elevated BNP levels often indicate heart failure, with higher levels correlating with more severe heart failure.
Key Points to Consider
- Age, sex, kidney function, and body mass can influence BNP levels, with levels typically higher in older individuals and those with reduced kidney function, while obesity may lead to lower BNP levels despite cardiac stress.
- BNP testing is commonly used in emergency settings to help diagnose or rule out heart failure in patients with shortness of breath or other cardiac symptoms.
- The following laboratory assessments should be performed at admission on the blood of all patients with AHF: cardiac troponin, blood urea nitrogen (BUN) (or urea), creatinine, electrolytes (sodium, potassium), liver function tests, thyroid-stimulating hormone (TSH) should be assessed in newly diagnosed AHF.
Factors Influencing BNP Levels
- Cardiac conditions such as heart failure, acute coronary syndromes, pulmonary embolism, myocarditis, left ventricular hypertrophy, hypertrophic or restrictive cardiomyopathy, valvular heart disease, congenital heart disease, atrial and ventricular tachyarrhythmias, heart contusion, cardioversion, ICD shock, surgical procedures involving the heart, and pulmonary hypertension.
- Non-cardiac conditions such as advanced age, ischaemic stroke, subarachnoid haemorrhage, renal dysfunction, liver dysfunction (mainly liver cirrhosis with ascites), paraneoplastic syndrome, chronic obstructive pulmonary disease, severe infections (including pneumonia and sepsis), severe burns, anaemia, and severe metabolic and hormone abnormalities.
From the Research
Normal BNP Levels
- A BNP level of less than 100 pg/mL is considered useful in diagnosing heart failure in symptomatic patients without a history of heart failure 2.
- In patients with acute heart failure, a BNP level < 100 pg/mL was found in only 10% of the patients 3.
- A goal to maintain a BNP concentration of less than 100 pg/mL has shown to correlate with functional improvement in patients with heart failure and has tended to decrease clinical endpoints, such as cardiovascular death 2.
- BNP levels are potentially more useful when a baseline concentration is known for a patient, because BNP levels are proportional to the severity of heart failure 2.
BNP Levels in Different Patient Groups
- Patients with a BNP level < 100 pg/mL were similar in age and sex but had higher left ventricular ejection fraction, body mass index, and hemoglobin and hematocrit concentrations compared with those with BNP levels > or = 100 pg/mL 3.
- In clinically stable patients with a recent admission for decompensated HF, only 10% had BNP levels < 100 pg/mL 3.
- Patients with low BNP levels seemed to have less severe HF and more frequently had preserved systolic function compared with patients with BNP levels > or = 100 pg/mL 3.
BNP-Guided Therapy
- Plasma brain natriuretic peptide (BNP) indicates the severity of left ventricular dysfunction 4.
- Hormone-guided therapy using plasma N-BNP levels resulted in fewer clinical end points than did clinical management 4.
- A BNP-guided strategy reduced the risk of CHF-related death or hospital stay for CHF in optimally treated CHF patients 5.