: N-terminal Pro-B-type Natriuretic Peptide, Serum or Plasma, Substance Concentration

: What Is NT-proBNP?

: NT-proBNP (N-terminal pro-B-type natriuretic peptide) is a fragment of a hormone produced by heart muscle cells. When the heart chambers are stretched—such as from increased pressure or fluid overload—the cells release a precursor that is split into an active hormone (BNP) and the inactive NT-proBNP fragment. Because NT-proBNP circulates longer in the blood, it is a useful indicator of how much stress the heart is under.

: How the Test Is Used

: Clinicians order an NT-proBNP measurement to help determine whether a person's symptoms—such as shortness of breath, fatigue, or swelling—may be caused by heart failure. It is often used alongside a physical exam, history, and other tests like an electrocardiogram or echocardiogram. Results are interpreted in context; they are not a stand-alone diagnosis.

: What the Result Means

: NT-proBNP concentrations tend to rise when the heart is under increased strain and are generally lower when the heart is not stressed. However, many factors can influence the level, including age, kidney function, body weight, and other medical conditions. Because reference ranges and decision thresholds vary by laboratory and clinical setting, your clinician will interpret your result relative to your specific circumstances rather than against a single universal cutoff.

: Preparing for the Test

: An NT-proBNP test is a routine blood draw, usually from a vein in the arm, and typically requires no special preparation such as fasting. Tell your clinician about all medications, supplements, and known health conditions, since these can affect interpretation. Follow any specific instructions your laboratory or care team provides.