D-Dimer
D-dimer is a small protein fragment left behind when a blood clot dissolves. A blood test measures how much of it is circulating.
Because D-dimer rises when clots are forming and breaking down, it is used to help evaluate whether a clotting condition might be present. It is especially useful for helping rule out certain clots when the result is normal. It is an acute, clinical-context test interpreted alongside symptoms and other findings.
A high D-dimer suggests increased clot formation and breakdown, but it is non-specific and rises with infection, inflammation, recent surgery, pregnancy, and age. It signals that further evaluation may be needed rather than confirming a clot. Because it is a clinical-context test, it is interpreted with your symptoms and imaging.
A low or normal D-dimer is often reassuring and, in the right context, helps make an active clot less likely. A low value is generally the expected, favorable finding.
A value within the normal range is typical when there is no significant active clotting. Your clinician will interpret your result based on the clinical situation in which it was ordered.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.