What is a Coagulation assessment?
The ability of blood to form clots involves proteins (also known as clotting factors) and platelets (also known as thrombocytes). The platelets are synthesized by the bone marrow. However, clotting factors are synthesized in the liver. This explains why patients with bone marrow or liver disease suffer from recurrent bleeding.
Assessing the ability to form clots involves a series of lab values. The most common tests are PT (known as prothrombin time) and PTT (known as partial thromboplastin time.) In many cases, the PTT test is performed with a prothrombin time (PT) test to give doctors a more complete picture of the clotting factors function.
Why it is done?
Coagulation assessment is useful in monitoring the effects of blood-thinning medications like Warfarin. They are also useful in other cases like vitamin K deficiency and liver disease. This is because clotting factors are made in the liver with the help of vitamin K.
Doctors also may order the PT and PTT tests to evaluate a bleeding disorder such as Von Willebrand disease or Hemophilia. Symptoms of these diseases include recurrent nosebleeds, heavy menstrual periods, gums bleeding, and easy bruising.
What happens during the procedure?
There is no special preparation is required for this test. Acquiring a blood sample for PTT and PT tests takes a few minutes, like any regular blood test. During the procedure, a needle is inserted into a vein in the arm or the hand, and blood is withdrawn and collected in a vial or syringe.
What to expect after Coagulation assessment?
You can return to your daily activities once the test is done. There may be some bruising, but it should go away in a day or so.
You could have your test results within hours if the laboratory analysis is done on-site. If your doctor sends your blood to an off-site laboratory, it may take several days to receive the results.
In some clinics, a nurse will take a sample of your blood with a finger stick, and give you the results within a few minutes.
The results of your PT and PTT values are compared with the average clotting time of a healthy person to see if you have any coagulation disorder (PT and PTT are measured in seconds).
PT and PTT values lower than the normal range means that your blood clots more quickly than normal. This puts you at risk of developing blood clots. Values higher than the average means that it takes a longer time for your blood to form clots. This puts you at risk of bleeding.
If your blood is clotting faster than normal, then this could indicate that you are on estrogen-containing medications like hormone replacement therapy and birth control pills.
If it takes a longer time for your blood to clot, this indicates vitamin K deficiency, liver problem, or you are on a blood-thinning medication like warfarin.
Your healthcare provider will advise you on the best course of action if you have abnormal PT/PTT values. You also may be referred to a hematologist for further investigations.
Mayoclinic: Prothrombin time test
John Hopkins: Blood Test: Partial Thromboplastin Time (PTT)