From the Guidelines
A normal BNP level is generally considered to be less than 100 pg/mL in healthy individuals, as indicated by the most recent and highest quality study 1.
Normal BNP Levels
When evaluating BNP levels, it's essential to consider the context and potential influencing factors.
- BNP is a hormone released by the heart when it's under stress, particularly when the heart's chambers are stretched due to increased blood volume or pressure.
- Elevated BNP levels often indicate heart failure, with higher levels correlating with more severe heart failure.
- Other conditions that can raise BNP include kidney disease, pulmonary embolism, and severe lung disease.
- Age, gender, and body mass index can also influence BNP levels, with levels typically increasing with age and being higher in women than men.
- Obesity can actually lower BNP levels, which should be considered when interpreting results in overweight patients.
Clinical Considerations
In clinical practice, BNP levels are used to help differentiate between cardiac and non-cardiac causes of acute dyspnea, with normal levels making the diagnosis of acute heart failure unlikely 1.
- The European Society of Cardiology guidelines recommend measuring plasma NP levels, including BNP, in all patients with acute dyspnea and suspected acute heart failure.
- Thresholds for normal BNP levels are generally considered to be less than 100 pg/mL, while NT-proBNP levels are typically less than 300 pg/mL.
- It's crucial to consider the individual patient's context and potential influencing factors when interpreting BNP levels, as elevated levels can be associated with a wide range of cardiac and non-cardiac conditions.
Laboratory Tests
Laboratory tests, including BNP and NT-proBNP, should be performed at admission on the blood of all patients with acute heart failure, along with other assessments such as cardiac troponin, blood urea nitrogen, creatinine, electrolytes, and liver function tests 1.
- These tests help identify patients at risk of poor prognosis and guide optimal management.
- Pre-discharge assessment of NPs may be considered for prognostic evaluation, and more frequent testing may be justified according to the severity of the case.
From the Research
Definition of Normal BNP Levels
- The definition of a normal BNP level can vary depending on the study and population being examined 2, 3, 4, 5.
- According to some studies, a BNP level of less than 100 pg/mL is considered normal or diagnostic for patients without heart failure 2, 3.
- However, other studies suggest that the normal range for BNP levels may be lower, around 40 pg/mL or less, especially in younger patients and those without heart failure 5.
Factors Affecting BNP Levels
- BNP levels can be affected by various factors, including age, sex, body mass index, and the presence of heart failure or other cardiac conditions 2, 3, 4, 5.
- Older patients tend to have higher BNP levels, even in the absence of heart failure, due to age-related changes in cardiac function 5.
- Patients with heart failure or left ventricular dysfunction tend to have higher BNP levels, which can be used as a diagnostic and prognostic marker 2, 3, 4.
Clinical Significance of BNP Levels
- BNP levels can be used to diagnose and monitor heart failure, as well as to guide treatment decisions 2, 3, 6.
- A BNP level of less than 100 pg/mL may indicate a lower risk of heart failure or cardiac events, while higher levels may indicate a higher risk 3, 4.
- However, BNP levels should be interpreted in the context of other clinical factors and diagnostic tests, as they are not specific for any particular disease state 3.