• What it tests for: The BNP test measures the level of B-type natriuretic peptide (BNP), a hormone released by the heart when it is under increased pressure or strain. It is primarily used to help diagnose or monitor heart failure and to help determine whether shortness of breath is caused by a heart condition rather than a lung problem.

• Sample needed: A venous blood sample collected in a blood tube (typically EDTA/plasma, depending on the laboratory's testing method).

Higher BNP levels may suggest heart failure or increased stress on the heart, although results should always be interpreted alongside the patient's symptoms, medical history, and other diagnostic tests.