Testing For Clotting Tendencies (Thrombophilias)

If blood clots occur in more than one person in a family, there may be an inherited clotting disorder. Genetic mutations can cause defective blood clotting factors. Factor V (five) Leiden and the prothrombin gene mutations are among the most commonly encountered gene mutations in the community. Individuals who inherit one of these mutations from either parent (heterozygous) may experience recurrent episodes of DVT, but the risk is highest if both parents were affected (homozygous).

Other inherited causes include abnormalities of certain blood components (antithrombin, protein C, and protein S deficiency) that ordinarily help dissolve blood clots.

Some genetic mutations can lead to increased amounts of homocysteine in the circulation. Homocysteine is a compound that increases the tendency for the blood to clot, as well increasing the risk of stroke and heart attack.

Blood tests are available to look for these abnormalities. Unless there is a personal history of a previous DVT, Medicare Australia does not cover the cost of these tests. In case of a family history of clotting, Medicare Australia only covers certain tests. Presence of thrombophilic abnormalities in general does not change the managemnt of DVT and appears not to increase the risk of recurrent DVT.

Certain tests such as Factor Xa Clotting Time (XACT), Rotational Thromboelastometry (ROTEM) and platelet function studies (MULTIPLATE) can be done in-house at the Phlebology Research Lab. These tests can further help with the assessment of the underlying clotting tendencies.