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By Dr B V S Apoorva
Consultant Pulmonologist
What is it used for? What happens during a PTT test? How do I prepare for the test? Are there any risks to the test? What do the results mean? Frequently Asked Questions

Partial Thromboplastin Time (PTT) Test

The partial thromboplastin time (PTT) test evaluates the blood's clotting ability by measuring the time it takes for a blood sample to clot. When bleeding due to an injury or a cut, various proteins in the blood collaborate to form a clot, which halts the bleeding. These proteins are referred to as coagulation factors or clotting factors.

A PTT test is used to screen for a specific group of clotting factors. It can assist in determining how many of these clotting factors one has and how well one performs.

A PTT test is frequently carried out along with other tests that assess clotting factors and how well they all work together.

What is it used for?

A PTT test is performed to look for problems with a particular group of blood clotting factors. The test is performed to:

  • Identify the cause of excessive bruising or bleeding.
  • Find the cause of clotting issues. Some autoimmune illnesses, such as lupus and antiphospholipid syndrome, can be the cause.
  • Those taking heparin, a medicine used to prevent and treat blood clots, should be closely monitored. PTT testing can assist in ensuring that the dose is safe and effective.
  • Before undergoing surgery or other medical treatments, assess the risk of bleeding.

What happens during a PTT test?

A small needle will be used by a healthcare professional to draw blood from a vein in the arm. After inserting the needle, a small amount of blood will be collected in a test tube or vial. When the needle goes in or out, you may feel a slight sting. This usually takes under five minutes.

How do I prepare for the test?

A PTT test does not necessitate any special preparation.

Are there any risks to the test?

Having a blood test poses very little risk. Individuals may experience minor pain or bruising where the needle was inserted, but most symptoms will subside quickly.

What do the results mean?

The PTT test results will indicate how long it took for your blood to clot. The results are usually given in seconds. A PTT test is frequently ordered with a prothrombin time (PT) test.

A PT test checks for clotting factors that a PTT test does not. The provider will usually compare the results of both tests to understand how your blood clots. Inquire with your provider about the implications of the test results for your health.

In general, if the blood took longer than usual to clot on a PTT test, this could indicate:

  • A lack of vitamin K
  • Liver disease
  • Certain genetic disorders that individuals inherit from their parents. These disorders interrupt certain clotting factors, increasing the risk of bleeding. They include:
    • Von Willebrand disease
    • Hemophilia
  • Certain types of leukemia
  • Too much heparin
  • Autoimmune diseases

If the blood clot faster than usual on a PTT test, this could indicate:

  • Disseminated intravascular coagulation in its early stages (DIC). If you have an infection or damage to organs or tissues that affects blood clotting, you may develop this rare but serious condition. Individuals have excessive blood clotting in the early stages. Later, DIC begins to deplete clotting factors in the blood, resulting in bleeding problems.
  • Cancer of the ovaries,colon, or pancreas has spread to other body parts and is unlikely to be controlled through treatment.

Discuss the test results with the healthcare provider to learn what they mean.

Frequently Asked Questions

1. What are the normal PTT levels?

The normal range for PTT levels varies according to the laboratory that performs the test. A PTT result of 25-35 seconds is considered normal in most cases.

2. What does an abnormal PTT result mean?

An abnormal PTT result may indicate a bleeding disorder or an increased risk of bleeding due to using blood-thinning medications.

3. What factors can affect PTT levels?

PTT levels can be affected by medications such as heparin and warfarin. PTT levels can also be affected by liver disease, vitamin K insufficiency, and lupus anticoagulants.

4. Can PTT results be affected by pregnancy?

Yes, pregnancy can affect PTT levels. Pregnancy is associated with increased levels of clotting factors, which can cause a shorter PTT time.

5. How long does it take to get PTT test results?

Depending on the laboratory administering the test, PTT test results are normally available within a few hours to a few days. Your healthcare provider will discuss the results with you and recommend any necessary further testing or treatment.

6. What is the difference between PTT and INR tests?

The PTT test measures the time it takes for blood to clot, while the International Normalized Ratio (INR) test measures how long it takes for blood to clot compared to a control sample. The INR test is used to monitor the effectiveness of the blood-thinning medication warfarin.

7. Can PTT testing diagnose pulmonary embolism (PE)?

No, PTT testing is not used to diagnose PE. Imaging tests such as CT scans or pulmonary angiography diagnose PE.

8. Can PTT testing be affected by the type of blood collection tube used?

Yes, PTT testing can be affected by the type of blood collection tube used.

9. How often should PTT levels be checked during heparin therapy?

PTT levels are usually checked every 6 hours during the first few days of heparin therapy and then less frequently once the desired therapeutic range is achieved.

10. What is the cost of a PTT test?

The cost of a PTT test ranges from Rs. 300 to Rs. 600.