PT and PTT Blood Test Results Fully Explained


The PTT blood test is generally used as a way to determine why there is either unexplained bleeding or inappropriate clotting. It is often order in conjunction with the PT blood test, which can provide a measurement of hemostasis.

Hemostasis is the process that is used by the body to be able to form a blood clot when there is bleeding somewhere. Because there are several proteins used in the process of forming clots, the PTT blood test looks at several prothrombin and fibrinogen factors, in addition to prekallikrein and kiniogen factors to determine the status of bleeding and clotting.

By combining the PT and PTT blood test results together, it becomes possible to determine the potential cause for a bleeding or clotting disorder. The results are not able to provide a diagnosis in most cases, but do allow a medical provider to order the next tests that may be needed to create a treatment plan.

When to Ask About the PT and PTT Blood Test

The PT and PTT blood test will often be ordered whenever someone has the signs and symptoms of inappropriate clotting, unexplained bleeding, or bruises easily. The potential presence of a blood clot in a vein or an artery will also trigger this test, as well as the rapid bleeding and clotting factors that get used at unusually high rates.

Some individuals who suffer from chronic liver disease may also have the PT and PTT blood test ordered to determine their hemostasis status.

It may also be ordered for women who have had recurrent miscarriages or there is a suspicion of an autoimmune disorder, such as lupus, that may be affecting personal health.

Individuals on herapin therapies or taking blood-thinning medications like Coumadin will also have these blood tests ordered on a frequent basis for monitoring purposes. Those with past bleeding disorders who may require surgery in the near future may also have this test ordered to determine the current status of their health.

What Do My PT and PTT Blood Test Results Mean?

PTT results are available very quickly as it only takes a few seconds to obtain results. A normal test result indicates that the blood is clotting as it should. Prolonged results indicate that clotting takes longer than it should to occur and this can be for a wide variety of reasons, from coagulation factor deficiencies to hemophilia to inherited genetic diseases.

Prolonged PT results may indicate liver disease or disseminated intravascular coagulation, along with decreased or defective factors.
When combined together, these PT and PTT results may indicate these common conditions.

Prolonged PT, Normal PTT: Indicates a vitamin K deficiency, decreased/defective factors, or liver disease.
Normal PT, Prolonged PTT: Indicates hemophilia, certain defective factors, von Willebrand disease, or the presence of a lupus anticoagulant.
Prolonged PT, Prolonged PTT: Indicates severe liver disease, genetic conditions, or decreased/defective factors.
Normal PT, Normal PTT: May indicate a mild deficiency or other factor or normal hemostasis.

Some individuals may have shortened PTT blood test results. This may indicate extensive cancer, unless there is known liver issue involved. It may also indicate an acute phase reaction that is causing a pronounced level of inflammation within the body that immediately elevates a specific factor level. Acute reactions will cause future PTT blood tests to return to a normal range.

Here’s What You Need to Know

There are certain anticoagulants that will not cause a prolonged PTT blood test result. Your medical provider will let you know if these are present and if they should be monitored through other forms of testing in addition to the PT and PTT blood tests.

Certain individuals with high hematocrit levels may have a prolonged PTT blood test result, but not actually have a health concern that needs to be addressed in this area. Heparin contamination may alter the results of the blood tests as well, especially if the blood is being collected from an IV line instead of a direct draw.

Certain drugs, such as aspirin, are also known to change the blood test results. Talk to your doctor if you regularly take antihistamines for seasonal allergies, vitamin C supplements, or chlorpromazine so the test results can be accurately reported.

By understanding how your blood is functioning, it becomes easier to determine why inappropriate clotting or unexplained bleeding is occurring and to be able to treat it. Speak to your doctor immediately if you suspect a blood clot or have a cut or bruise that continues to affect your health to determine if this testing is right for you.