CLINICAL USE OF D-DIMER
Since its introduction to clinical use, the D-dimer test for deep venous thrombosis/pulmonary embolism has been a blessing and a curse. What is the current thinking regarding D-dimer use in clinical practice?
—Donald S. Piland, MD, Poplar Bluff, Mo.
Among the general limitations of D-dimer testing is its nonspecificity. Positive results can occur, for example, in trauma, surgery, sepsis, and chronic inflammation. A second drawback is the use of different testing procedures by various kit manufacturers. Among available kits, enzyme immunosorbent assay (EIA)-based testing is usually more sensitive than other methods. A third problem is lack of standardization, limiting comparisons among reported studies. Nevertheless, for excluding thrombosis in symptomatic patients, a negative quantitative EIA result is as diagnostically useful as a negative result by duplex ultrasonography (Ann Intern Med. 2004;140:589-602). Also, if testing by D-dimer is combined with ultrasound imaging, repeat imaging can safely be avoided. In patients suspected of having acute recurrent thrombosis, measurement of D-dimer may be particularly useful in excluding the diagnosis, even given the fact that anticoagulated patients may have false-negative results. Data from one study were promising, although further studies in this clinical setting are clearly needed (Ann Intern Med. 2004;141:839-845).
—Dennis K. Galanakis, MD (106-7)