D-dimer trifecta: clarity on units, values, and use
January 2020—D-dimer has a problem. Several problems, in fact. Many, some might say. Let’s start with the basics regarding D-dimer assays: unit and magnitude. Setting up the equation is easy, and the digits are small: 2 × 4. When applied to D-dimer testing, however, the answer often means far-flung problems for laboratories and clinicians. Parsed out (for fans of James Thurber, this means channeling schoolmarm Miss Groby), D-dimer has two different units of measure. Some assays report fibrinogen equivalent units (FEU), and others measure D-dimer units (DDU).