Prothrombin Time (PT with INR)

A prothrombin time (PT) test analyzes blood samples to measure the time it takes for your blood to form a clot. When you get injured and begin to bleed, your body launches a step-by-step process that forms clots to stop the bleeding. This process involves clotting factors which include prothrombin and other proteins.

If the clotting process does not work, it means that your body doesn’t have enough of each clotting factor. It could also mean that all factors are not functioning as they are supposed to. If your blood clots too slowly, you may bleed excessively after an injury. On the other hand, if it clots too fast, there can be an increased risk of dangerous clots forming in your arteries or veins. In cases like these, a PT test can help check the speed at which your blood is clotting.

What Is Prothrombin?

Prothrombin is a protein produced by the liver. It is grouped under clotting (coagulation) factors along with several other substances, and is responsible for helping your blood to clot appropriately.

Why Should I Get A Prothrombin Time Test?

You may need a prothrombin time test if you are taking warfarin on a daily basis. Warfarin is a blood thinner that helps prevent blood clots. This can cause serious conditions such as deep venous thrombosis and pulmonary embolism. A PT test can help make sure that you’re taking the correct dose. On the other hand, you may need a PT test if you have symptoms of a clotting or bleeding disorder. 

 Symptoms of a clotting disorder include the following:

• Chest pain
• Leg pain and tenderness
• Swelling in the leg
• Redness or red streaking on the legs
• Rapid heartbeat
• Coughing
• Difficulty in breathing

Symptoms of a bleeding disorder are:

• Bruising easily
• Unexplained heavy bleeding
• Abnormally heavy nose bleeds
• Extremely heavy menstrual periods

You may also need a PT test if you are scheduled for surgery. It can help make sure that your blood is clotting properly so that you won’t lose too much of it during the procedure.

What Happens During The Test?

A prothrombin time test is typically a simple procedure. First off, your doctor will clean your skin with some alcohol. Then, they will place an elastic band around your upper arm and ask you to make a fist. This will allow your blood to flow more easily. Next, they will insert a needle and draw the blood. You might feel a stinging pain but it should last only for a second or so. After they’ve finished drawing blood, your doctor will put a small bandage on the spot.

What Are The Risks Associated With The Test?

A PT test normally takes a few minutes. It is a minimally invasive procedure that does not have risks associated with it. At most, you can experience slight soreness or minor bruising at the site in your arm where the blood was drawn. If you feel a lot of pain, do visit your healthcare provider for a check-up.

What Do PT Test Results Mean?

PT test results can be presented in two ways:

• In Seconds

The average time range for blood to clot is about 10-13 seconds. A number higher or lower than the range can hint at problems such as bleeding and clotting disorders.

• As INR

This ratio is used if you take blood-thinning medicines. It allows for easier comparisons of test results from different laboratories. For healthy people, an INR of 1.1 or below is considered normal. When your INR is higher or lower than the recommended range, you can be at risk of various conditions.