A normal D-dimer level is less than 250 micrograms per liter, or less than 1.37 nanomoles per liter. A level in this range indicates the presence of a small amount of the substance that is released when blood clots dissolve, indicating that there is likely not a blood clotting issue.
Doctors order a D-dimer test to determine if a person has a blood clotting problem, which sometimes occurs with conditions such as deep vein thrombosis or a pulmonary embolism, says WebMD. Physicians use the test to evaluate the effectiveness of clotting therapies and to adjust the treatment regimen accordingly. The test is a simple blood test that requires no special preparation from the patient.