Which condition can cause a false positive in D-dimer testing?

A false positive result in D-dimer testing can occur due to several underlying conditions, and infection is one of the notable causes. D-dimer is a fibrin degradation product that typically increases in the presence of clot formation and breakdown. Infections, particularly severe or systemic infections, can lead to inflammation and elevation of various acute phase reactants, including D-dimer levels. This elevated level may mimic or mask the presence of thrombotic disorders, leading to misleading test results.

Other conditions, while they may also be associated with elevated D-dimer levels, are less commonly known to cause false positives specifically due to the metabolic and homeostatic changes they induce. For instance, cardiovascular disease can lead to clot formation but does not inherently increase D-dimer for the same reasons an acute infection does. Similarly, hypertension and diabetes mellitus can affect overall health but are not direct causes of elevated D-dimer in the context of false positives seen with infectious processes. Thus, infection clearly stands out as a significant contributor to misleading D-dimer results.