Prothrombin, also known as PT, PTZ, is a protein produced by the liver. It is one of the substances that help blood clotting. The Prothrombin time test is a test that measures how long the blood clots. Pt test (Prothrombin time test) is performed by taking blood sample from the person’s vein and examining it in laboratory for example.
Coagulation factors are required for blood clotting. Prothrombin or factor II is one of the clotting factors produced by the liver. It is necessary to make vitamin K, prothrombin and other clotting factors. Prothrombin time is an important test because the blood controls the presence of five different coagulation factors (factors I, II, V, VII and X).
Prothrombin Time test (Pt test) normal values
The PT is measured in seconds. Often, results are announced under the INR (international normalized rate) test.
If you’re not taking blood thinners like Warfarin, the normal range of your PT results is:
11 to 13.5 (seconds)
0.8 to 1.1 INR
If you are using warfarin to prevent blood clots, your doctor will likely choose to keep INR between 2.0 and 3.0.
Why is a prothrombin time test (Pt test) performed?
Your doctor may require prothrombin time testing in the following cases:
- Monitor the effectiveness of the blood thinner drug you receive
- To diagnose liver problems
- To evaluate the blood clotting ability before surgery
- Prothrombin time testing is also one of several tests used for people waiting for liver transplantation.
- To determine the cause of bleeding or bruising
- To check if vitamin K is low. Vitamin K is a vitamin required for prothrombin and other coagulation factors.
- To check whether it is safe for a person to perform an operation that may cause bleeding
- Checking how well the liver works. Prothrombin levels are controlled with other liver tests such as aspartate aminotransferase and alanine aminotransferase.
What does the Pt test (Prothrombin time test) result in?
Causes of blood clotting slowly
Use of blood thinning drugs
Insufficient protein levels for blood clotting
Vitamin K deficiency
Over-activation of proteins controlling blood clotting (spreading intravascular coagulation)
Other substances in your blood may prevent clotting
Causes of blood clotting very fast
Vitamin K supplements
Excessive consumption of foods containing high amounts of vitamin K, such as liver, broccoli, chickpea, green tea, cabbage, turnip, and soybean products
Estrogen-containing drugs, such as birth control pills and hormone replacement therapy
Causes of Pt (Prothrombin time) elevation
- Bile duct obstructions
- Vitamin K deficiency
- Salicylate Intoxication
- Kumadin treatment
- Common intravascular coagulation (DIC)
- Massive blood transfusion
- Lack of hereditary factors
- Acquired or congenital deficiencies of Factors II, V, VII and X
- Oral anticoagulant therapy
- Liver disease
- Presence of inhibitor
- Biliary obstruction
- Zollinger Ellison syndrome