A doctor orders a D-dimer blood test if a person is showing signs of a deep vein thrombosis, a pulmonary embolism or the blood clotting condition called disseminated intravascular coagulation, according to MedlinePlus. The test is also ordered for those showing indications of a stroke.
The test measures a substance produced when a blood clot breaks down, notes WebMD. Any value less than 250 micrograms per liter or 1.37 nanomoles per liter is considered normal. Low or normal levels mean that an issue with blood clotting is unlikely. Elevated levels mean that a blood clotting problem is more likely.
A positive D-dimer test doesn't tell a physician where the blood clot is located, nor does it point to the cause of clotting, states Lab Tests Online. Furthermore, D-dimer levels can be elevated in other conditions such as trauma, cancer, post-surgery and infection. Heart attacks, liver disease, pregnancy and rheumatoid arthritis can also increase D-dimer levels. The usefulness of the test in children has not been adequately studied.
Risk factors predisposing people to the development of blood clots include prolonged immobility due to illness, injury or lengthy travel, major surgery or trauma, some cancers and the use of hormonal therapies such as birth control, according to Lab Tests Online. Obesity, smoking, pregnancy or recent childbirth and inherited clotting disorders are additional risk factors.