AorticDissection.com-D-Dimer Information Page
Here's are some good links on just what D-Dimer test is all
How is it used?
D-dimer tests are ordered, along with
other laboratory tests and imaging scans, to help rule out,
diagnose, and monitor diseases and conditions that cause
, a tendency to clot inappropriately. One
of the most common of these conditions is DVT (Deep Vein
Thrombosis) which involves clot formation in the deep veins of the
body, most frequently in the legs. These clots may grow very
large and block blood flow in the legs, causing swelling, pain,
and tissue damage. It is possible for a piece of the clot to
break off (this broken piece is called an embolus) and travel to
other parts of the body, where the clot can cause a PE (Pulmonary
embolus or embolism - blood clot in the lungs).
While clots most commonly form in the veins of the legs, they
may also form in other areas as well; for example, clots in
coronary arteries are the cause of myocardial infarction (heart
attacks). Clots may also form on the lining of the heart or
its valves, particularly when the heart is beating irregularly (atrial
fibrillation) or when the valves are damaged. Clots also may form
in large arteries as a result of damage from
atherosclerosis (sometimes called hardening of the arteries).
Pieces of such clots may also break off and cause an embolus that
blocks an artery in another organ, such as the brain (causing a
stroke) or the kidneys. Measurements of D-dimer can also be
used to detect clots in these other sites.
Measurements of D-dimer may also be ordered, along with other
tests, to help diagnose
DIC (Disseminated Intravascular Coagulation). DIC is a complex
acute condition that can arise from a variety of situations
including: some surgical procedures, septic shock, poisonous snake
bites, liver disease, and postpartum (after the delivery of a
baby). With DIC, clotting factors are activated and then used up
throughout the body. This creates numerous minute blood clots and
at the same time leaves the patient vulnerable to excessive
bleeding. Steps are taken to support the patient, while the
underlying problem is addressed, and the underlying condition
resolved. D-dimer levels may be used to monitor the effectiveness
of DIC treatment.
When is it ordered?
D-dimer may be ordered when a patient
has symptoms of DVT, such as leg pain, tenderness, swelling,
discoloration, edema; or symptoms of PE, such as labored
breathing, coughing, and lung-related chest pain. D-dimer is
especially useful when the doctor thinks that something other than
DVT or PE is causing the symptoms. It is a quick, non-invasive way
for the doctor to help rule out abnormal or excess clotting.
When a patient has symptoms of
DIC, such as bleeding gums, nausea, vomiting, severe muscle
and abdominal pain, seizures and oliguria (decreased urine
output), a D-dimer test may be ordered, along with a
platelet count to help diagnose the condition. D-dimer may
also be ordered at intervals when a patient is undergoing
treatment for DIC to help monitor its progress.
What does the test result mean?
NOTE: A standard reference range is not available
for this test. Because reference values are dependent on many
factors, including patient age, gender, sample population, and
test method, numeric test results have different meanings in
different labs. Your lab report should include the specific
reference range for your test. Lab Tests Online strongly
recommends that you discuss your test results with your doctor.
For more information on reference ranges, please read
Reference Ranges and What They Mean.
A positive D-dimer indicates the
presence of an abnormally high level of fibrin degradation
products in your body. It tells your doctor that there has been
significant clot (thrombus) formation and breakdown in the body,
but it does not tell the location or cause. An elevated D-dimer
may be due to a VTE or
but it may also be due to a recent surgery, trauma, or
infection. Elevated levels are also seen with liver disease,
pregnancy, eclampsia, heart disease, and some cancers.
A normal D-dimer test means that it is most likely that you do
not have an acute condition or disease that is causing abnormal
clot formation and breakdown. Most doctors agree that a negative
D-dimer is most valid and useful when the test is done on patients
that are considered to be low-risk. The test is used to help rule
out clotting as the cause for the symptoms.
D-dimer is recommended as an adjunct test. It should not be the
only test used to diagnose a disease or condition. Both increased
and normal D-dimer levels may require follow-up and can lead to
Is there anything else I should know?
therapy can cause a false negative D-dimer.
There are several different methods of testing for D-dimer. Most
of the D-dimer tests that yield
are done in a hospital lab, while those
are performed at the patientís bedside.
D-dimer concentrations may rise in the elderly, and false
positives may be seen with high levels of
rheumatoid factor (a protein seen in patients with rheumatoid
arthritis). Substances such as high
triglycerides, lipemia (a large amount of fats in the blood
that can be caused by the patient consuming a greasy meal prior to
bilirubin can also cause false positives as can
hemolysis caused by improper collection and handling.