What diagnostic test measures B-type natriuretic peptide levels in the bloodstream?

The diagnostic test that measures B-type natriuretic peptide (BNP) levels in the bloodstream is the BNP Test. This test is crucial in the clinical assessment of heart failure. BNP is a hormone that is produced by the heart's ventricles in response to excessive stretching of heart muscle cells, which often occurs when the heart is under stress due to conditions like heart failure. When elevated, BNP levels can help differentiate between heart failure and other causes of dyspnea, guiding treatment and management plans.

The other diagnostic options, while valuable for various cardiac assessments, do not specifically measure BNP levels. An echocardiogram assesses cardiac structure and function via ultrasound, providing images of the heart rather than biochemical data. An electrocardiogram records the electrical activity of the heart but does not quantify BNP levels. A chest X-ray can visualize heart size and lung congestion but does not offer specific information about BNP levels. Therefore, the BNP Test is the definitive measure for gauging this particular biomarker in relation to heart function.