Partial Thromboplastin Time

How does a partial thromboplastin time test work?

Once a provider has your blood sample in a lab, they’ll:

1. Separate out the part (plasma) they need.
2. Add an activator to your plasma.
3. Incubate your plasma.
4. Add calcium chloride to complete the activation. This triggers clot formation.

The time it takes (in seconds) for a clot to form is your partial thromboplastin time.

How do I prepare for a partial thromboplastin time test?

You don’t have to do anything to prepare for a partial thromboplastin time test. But drinking a lot of water before your blood draw can make it easier for a provider to find a plump vein to puncture. You may want to wear a shirt with short sleeves so you don’t have to roll up your sleeve.

What should I expect during a partial thromboplastin time test?

A healthcare provider will take a blood sample from your vein. They’ll put it into a tube that has a substance in it to keep it from clotting while it’s in the tube.

The steps a provider will follow are:

1. Ask you to sit with your arm out in front of you. It’ll likely be a special chair with an armrest where you can stretch your arm out.
2. Tie a band around your upper arm.
3. Clean a small area of skin on your arm.
4. Put a small needle into the skin they just cleaned.
5. Use the needle to get blood from your vein and into a tube.

What can I expect after a partial thromboplastin time test?

After a provider takes a blood sample, they’ll:

1. Take the band off your upper arm.
2. Take the needle out of your arm.
3. Press a cotton ball or something similar on the area where they removed the needle.
4. Put a bandage on the area they punctured.

What are the risks of a partial thromboplastin time test?

You’ll feel a quick needle puncture that feels like a pin pricking your skin. You might have a bruise around the area where the needle went into your skin. This should go away in a few days.

What type of results do you get and what do the results mean?

Partial thromboplastin time test results are the number of seconds your blood needs to make a clot. A clotting time between 25 and 35 seconds is in the partial thromboplastin time normal range. This normal range may vary a bit from lab to lab.

What does it mean when your PTT is high?

If your partial thromboplastin time test result is high, it means your blood is taking longer to clot than it should. This could mean:

• Your heparin dose is too high.
• You have an autoimmune disease that affects clotting.
• You have liver disease.
• You have a type of leukemia that affects clotting.
• You inherited a genetic issue like hemophilia or von Willebrand disease from your parents.
• You don’t have enough vitamin K in your body.

When should I know the results of a partial thromboplastin time test?

It depends on the lab you use. You may get results of a partial thromboplastin time test the same day or in a few days.

If the results are abnormal, what are the next steps?

If you have abnormal results from your partial thromboplastin time test, the next step could be:

• More testing to figure out if you have a specific condition, like an issue with one of your clotting factors.
• A different dose of heparin.

When should I call my doctor?

Contact your healthcare provider if the time frame they gave you for getting your results has come and gone without results. After you have your results, contact your provider if there’s anything that isn’t clear about your results or next steps.