Activated Partial Thromboplastin Time (APTT)

Hemophilia, von Willebrand Disease, Liver-related disease

aPTT Test is the short-form of Activated Partial Thromboplastin Clotting Time test.

The aPTT test is a diagnostic test that gives an idea about how well your body’s coagulation mechanism is working by determining the time it takes your body to form a clot at a site where bleeding has occurred.

Coagulation is defined as the automatic blood clotting process at the site of bleeding. Many factors come into play to convert the flowing blood into a semi-solid substance that prevents blood loss.

When you undergo the aPTT Test, it evaluates and reports the time it takes your body to undergo this entire process.

Your healthcare practitioner will only suggest you take the aPTT Test if they see signs of prolonged clotting time, which can be harmful to your health or undergoing some therapy or surgery that can lead to blood loss. Increased aPTT from the normal range may indicate that your body is not prepared for the therapy, liver-related diseases, Hemophilia, etc.

Further, aPTT Test during pregnancy rules out the risk concerning the chances of a miscarriage. This is because a low-activated partial thromboplastin clotting time (or aPTT) can lead to a miscarriage by forming blood clots in the body.

One of the factors responsible for maintaining the aPTT at a good value is Vitamin K. If there is a Vitamin K deficiency, your body may develop a prolonged aPTT, which can have consequences on your health. The Indian diet can sometimes become Vitamin K deficient because of not consuming enough Vitamin K, which may sometimes lead to a prolonged clotting time.

Other Names for the aPTT Test

What Does aPTT Test Measure and Who is This Prescribed For?

The aPTT Test measures the time it takes your body to form clots in case of any injury.

Doctors prescribe the aPTT Test in the following conditions:

• Diagnose Hemophilia: Hemophilia is a blood disorder in which the clotting process does not take place properly. There are specific clotting factors that are evaluated to determine the clotting time. Here, the aPTT Test is used for the diagnosis of Hemophilia. It is done by seeing if any of the clotting factors are present in lesser quantities than what is considered to be normal.
• Diagnose von Willebrand Disease: This is a hereditary disease related to platelet dysfunction, which leads to an increase in clotting time. So, taking the aPTT Test can help in the diagnosis of this disease.

• Monitor the progress of Heparin Therapy: Heparin Therapy aims to get the Activated Partial Thromboplastin Clotting Time (or aPTT) within a therapeutic range. This range often varies from one medical institute to another. However, the aPTT Test is used in all medical institutions to monitor how well the therapy is working for patients undergoing this therapy.

Other than people in the above-stated conditions, the aPTT Test is also suggested to people who show the following symptoms:

• If you are bleeding or bruising easily.
• Blood clots form when they shouldn’t.
• Blood in your urine or excreta.
• Easily bleeding gums.
• Experiencing heavy menstrual periods.
• Nose bleeding.
• Swelling or pain in the joints.

You should refer to the following table of range to interpret your test results:

The aPTT Test results can often vary from lab to lab because of the different equipment used to conduct tests on the collected aPTT Test blood sample.

The Activated Partial Thromboplastin Clotting Time (or aPTT) can vary for some groups, which should be kept in mind while getting the aPTT Test done.

• For children: The time it takes for a child’s body, especially infants in the age group of 1 to 6 months, to clot at the bleeding site is usually longer than what it takes an adult. Keeping this in mind, the reference range for normal aPTT will also be different for children and should be interpreted according to the lab’s standards.
• For pregnant women: For pregnant women, the aPTT can come out to be higher than the normal aPTT range. So, a pregnant woman’s results should be interpreted differently. The lab technician or the doctor should be consulted to interpret the aPTT Test results.

However, here is what each test result means:

• Lower than normal aPTT

This indicates that your body is taking less time than it should to clot. A few factors that can result in a lower-than-normal aPTT are:

• If you are in the early stages of ​​Disseminated intravascular coagulation (DIC).
• If you have advanced cancer of the ovaries, pancreas or colon.
• If you have an acute-phase reaction due to tissue inflammation or trauma that has decreased the aPTT.
• Normal aPTT

A normal aPTT indicates that your body is taking the right amount of time to form a clot. However, this is usually not a confirmation of any disease. If you still have any warning signs or symptoms, your doctor might suggest you go for further diagnostic tests.

• Higher than normal aPTT

A higher than normal aPTT indicates that your body is taking more than normal time to form a clot. This can be caused by an underlying health issue, which may be showing up in symptoms. Some health issues related to a high aPTT are Hemophilia, liver bleeding disorder, Vitamin K deficiency, etc.

The aPTT Test blood sample is collected from the patient. It is then tested with several chemicals to determine the time it takes to form a clot.

aPTT Test Preparation

aPTT Test preparation does not require much from the patient. There is no fasting required and you can continue to eat and drink healthy before giving your aPTT Test blood sample.

If you are taking regular medications like supplements or blood thinners, your doctor may ask you to stop taking them before giving your blood sample. Consult first. This happens because some medicines can interfere with the actual test results and so should not be taken before the sample is collected for testing.

The blood will be drawn from a vein in your arm and might prick a little when the needle is inserted. However, this procedure does not involve significant risks and does not need any extra preparation from your side.

After giving the aPTT Test blood sample, you might feel a little discomfort or even dizziness and weakness; however, these go away quickly and do not last long. Despite this, you should bring someone with you who can drive you back home if you feel uncomfortable.

Test Inclusions: What Parameters Are Included?

aPTT Test Parameters

The aPTT Test is often used to investigate bleeding or any clotting incidents and sometimes even to eliminate the chances of bleeding or a clotting disease. This test is often ordered along with a Prothrombin Time (PT) Test. The results of both tests, in conjunction, help the healthcare professional to determine the cause of a bleeding or clotting disorder.

The PTT and PT test each evaluates certain coagulation factors responsible for causing the clotting mechanism to work in case of an injury that results in bleeding.

• The aPTT Test is used to evaluate specific coagulation factors. These factors are Coagulation Factors XII, XI, IX, VIII, X, V, II (also called Prothrombin) and I (also called Fibrinogen). It also includes factors called Prekallikrein (PK) and high molecular weight kininogen (HK).
• Whereas a PT Test evaluates the specific coagulation factors VII, X, V, II and I (also called Fibrinogen).

How Frequently Should You Take the aPTT Test?

The aPTT Test is not supposed to be a part of your routine health check-up unless you are undergoing Heparin Therapy. Your doctor will only instruct you to take the aPTT Test when they find symptoms indicative of an abnormal aPTT or when you are supposed to undergo surgery.

An APTT  test may have different costs depending on the city and the laboratory. Generally, the price for an APTT test falls within the range of INR 559 to INR 1649. Here's a breakdown of the average expenses for an APTT test in select major cities in India: