Natriuretic Peptide Tests (BNP, NT-proBNP)

The natriuretic peptide tests, including B-type natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-proBNP), are blood tests used to diagnose and monitor heart failure.

What are BNP and NT-proBNP?

BNP and NT-proBNP are hormones produced by the heart in response to strain or stretching of the heart muscle cells, which can occur with heart failure. BNP is a peptide hormone that is released from the ventricles in response to increased wall stress, while NT-proBNP is a prohormone that is released along with BNP and has a longer half-life.

How are the tests performed?

The BNP and NT-proBNP tests involve taking a blood sample from a vein in the arm. The blood is then sent to a laboratory for analysis, where the levels of BNP or NT-proBNP are measured using an immunoassay.

What do the results mean?

The results of the BNP and NT-proBNP tests can help diagnose heart failure and monitor its severity. Elevated levels of BNP or NT-proBNP in the blood indicate that the heart is under strain, which can occur with heart failure.

• Normal values: Less than 100 pg/mL for BNP and less than 300 pg/mL for NT-proBNP.
• Borderline values: 100-300 pg/mL for BNP and 300-600 pg/mL for NT-proBNP. These values may indicate mild heart failure or other conditions such as pulmonary embolism or acute coronary syndrome.
• Elevated values: Greater than 300 pg/mL for BNP and greater than 600 pg/mL for NT-proBNP. These values are often seen in patients with moderate to severe heart failure.

Clinical applications

The BNP and NT-proBNP tests have several clinical applications, including:

• Diagnosis of heart failure: To help diagnose heart failure in patients presenting with symptoms such as shortness of breath, fatigue, or swelling.
• Risk stratification: To assess the severity of heart failure and predict outcomes such as mortality and hospitalization.
• Monitoring treatment: To monitor the effectiveness of treatments for heart failure, such as medications or devices.

Limitations and potential interferences

The BNP and NT-proBNP tests are not perfect and can be influenced by several factors, including:

• Renal function: Impaired renal function can lead to elevated levels of BNP and NT-proBNP.
• Obesity: Obesity can lead to lower levels of BNP and NT-proBNP.
• Aging: Older adults may have higher levels of BNP and NT-proBNP due to age-related changes in the heart.

It is essential to consider these limitations when interpreting the results of the BNP and NT-proBNP tests and to use them in conjunction with other diagnostic tools, such as echocardiography and clinical evaluation.

Frequently Asked Questions (FAQs)

What is a Natriuretic peptide test?
Measures BNP or NT-proBNP levels in blood to diagnose heart failure.

What does BNP stand for?
Brain Natriuretic Peptide.

What does NT-proBNP stand for?
N-terminal pro b-type natriuretic peptide.

Why is the test ordered?
To diagnose or rule out heart failure.

How is the test performed?
Blood sample is taken from a vein.

What can high levels indicate?
Heart failure or other cardiac conditions.

Can the test be used for monitoring?
Yes, to monitor treatment of heart failure.

Are there any preparations needed?
No special preparation is required.

How long does it usually take to get results?
Typically within a few hours to a day.

What are normal levels of BNP and NT-proBNP?
Vary by lab, but generally <100 pg/mL for BNP and <300 pg/mL for NT-proBNP.