Coagulation Factor Tests

Coagulation Factor Tests

Coagulation factor tests are done to measure the levels of proteins in the blood, which are important for blood clotting or coagulation. The tests are usually ordered to diagnose or monitor people whose level of a certain clotting factor is too high or too low. Abnormal levels of coagulation factors are a sign of a bleeding or clotting disorder.

Preparation for Coagulation Factor Tests

Generally, no special preparation is needed before a coagulation factor test. However, a person should always inform their doctor if they are taking any medications, including over-the-counter drugs or supplements.


The procedure for a coagulation factor test is straightforward. After a venipuncture is performed, a sample of a person’s blood is collected in one or more vials. During this process, the puncture site may be covered with a bandage.

Once the sample is collected, it is sent to a laboratory for testing. The laboratory technicians measure the levels of specific coagulation factors in the sample using specific tests. They also measure the levels of clotting substances in the sample, known as inhibitors, to ensure proper blood clotting. The results are reported to the doctor, who interprets them and provides the patient with a diagnosis.

Types of Coagulation Factor Tests

There are several types of coagulation factor tests. Some of the most commonly used tests are:

  • Prothrombin time (PT) Test: Used to measure the activity of the coagulation factors I, II, V, VII, and X and to measure the effects of the anticoagulant medication warfarin (Coumadin)
  • Partial thromboplastin time (PTT) Test: Used to measure the levels of coagulation factors VIII, IX, XI, and XII and to determine if any of the coagulation factors are deficient
  • Thrombin time (TT) Test: Used to measure the levels of clotting factor II and to determine if it is defective
  • Factor tests: Used to measure the levels of individual coagulation factors, such as factors II, V, VII, VIII, IX, X, XI, and XII


Venipuncture is associated with very few risks. It may cause some minor bleeding at the puncture site, but this can usually be stopped by applying pressure to the site. Rarely, it may cause lightheadedness, fainting, hematoma (a lump under the skin from a buildup of blood), or infection.

When to get a Coagulation Factor Test?

A coagulation factor test is usually ordered when a person is experiencing abnormal bleeding or clotting. Such signs and symptoms may include bruising easily, nosebleeds, heavy menstrual bleeding, blood in the urine or stool, and stroke or heart attack. It may also be ordered as part of a routine physical exam, especially if a person has a family history of bleeding or clotting disorders.

Why Get a Coagulation Factor Test?

Coagulation factor tests are done to measure the levels of proteins in the blood, which are important for blood clotting or coagulation. Abnormal levels of these proteins can be caused by a number of conditions, including genetic disorders, diseases, medications, and vitamin deficiencies. The tests can help diagnose these conditions, enabling doctors to provide the patient with the proper treatment.