Activated partial thromboplastin time is a routine laboratory test that is used for the estimation of blood coagulation, i.e., intrinsic and common pathways. Moreover, it is also referred to as APTT blood test measuring the time for plasma clotting following the addition of certain specific reagents. Physicians order an APTT test because of purpose-specific panels due to suspected bleeding disorders, heparin therapy monitoring, or disease like hemophilia. It is a component of the general coagulation profile that delivers bleeding and safe anticoagulation management abnormalities diagnosis.

What is an APTT Test?

APTT stands for Activated Partial Thromboplastin Time, a lab test to measure the body's ability to clot blood to form blood clots. The APTT laboratory test directly measures the function of the intrinsic and common coagulation cascade, i.e., factors XII, XI, IX, and VIII, and factors X, V, II (prothrombin), and fibrinogen.

The test is highly valuable in the diagnosis of cryptic bleeding or coagulation disorders and is a highly valuable test to monitor for heparin therapy, particularly in inpatients. APTT testing is also often ordered as part of an extended coagulation panel that may be ordered prior to surgeries or to screen for diseases such as Hemophilia. APTT test abnormalities usually suggest a deficiency in a clotting factor or the presence of inhibitors in the blood.

Purpose of the APTT Test

The APTT test purpose or Uses of APTT in monitoring heparin therapy are:

  • Identification of intrinsic coagulation deficiencies
  • Diagnosis of inherited bleeding disorders, which includes hemophilia diagnosis test
  • Monitoring of heparin-based anticoagulation (when used in combination with the uses of APTT in heparin therapy monitoring)
  • It can also be used as a screening test for lupus anticoagulant and in the evaluation for unexplained bleeding or clotting.

When is the APTT Test Done?


Diagnosis of Bleeding and Clotting Disorders

An APTT test result will normally screen for disorders like hemophilia, von Willebrand disease, and even for lupus anticoagulant. In the case of abnormally prolonged APTT, factors or inhibitors can be missing. APTT shortened may suggest prothrombotic diseases.

Monitoring Anticoagulation Therapy

It is extremely important in APTT applications for heparin therapy monitoring-heparin prolongs APTT, and levels should be 1.5–2.5× control or approximately 60–80 seconds.

Specific Situations

APTT test in pregnancy, clotting is slightly shorter than APTT shortens (component of APTT vs PT testing). In coagulation profile tests, it also helps test cases of liver disease or vitamin K deficiency.

How to Prepare for an APTT Test?

APTT test procedure requires following preparations:

  • No fasting is necessary, but no lipemic interference, no heavy fat meal.
  • Let your laboratory know all of your medicines and supplements, especially the anticoagulants heparin or warfarin.
  • If on intermittent heparin, draw blood before next dose to show a trough level.

APTT Test Preparation

  • Phlebotomist draws a blood sample in a sodium citrate tube.
  • Sample spun down; obtained platelet-poor plasma.
  • Lab adds calcium, phospholipid, and activator (eg, kaolin).
  • Clotting time recorded in seconds by optical or mechanical methods.
  • Typical turnaround: 1–4 hours.

Read More: Renal Function Test (RFT): Types, Normal Ranges, and Kidney Health Insights


What to Expect After the APTT Test?

  • You should be mobile right away with usual activities.
  • A little tenderness or bruising can occur at the injection site.
  • Results are available in seconds, representing the amount of time your intrinsic pathway takes to clot.

Interpretation of APTT Test Results


Normal Range for APTT

  • Usually is 25–35 seconds, though norms may vary from lab to lab.
  • Normal APTT range is ~25–40 sec
  • APTT therapeutic ranges (heparin monitoring): approximately 60–80 sec (or ~1.5–2.5× control)

Interpretation of Abnormal Results

  • High APTT levels (>40 sec) may signal factor deficiencies, liver disease, heparin therapy, hemophilia, lupus anticoagulant.
  • Low APTT causes: with rising factor VIII, initial DIC, or some cancers.

Conditions Diagnosed with APTT Test

APTT test is an important diagnostic test to detect different blood clotting disorders and abnormalities of the coagulation process. The important conditions it detects are as follows:

  • Hemophilia Diagnosis Test: An increase in Activated Partial Thromboplastin Time (APTT) is a common indicator of Hemophilia A (factor VIII deficiency) or Hemophilia B (factor IX deficiency). In both disorders, the intrinsic coagulation pathway is disrupted, and clotting times are prolonged.
  • von Willebrand Disease and Lupus Anticoagulants: The APTT on blood can also be disrupted in von Willebrand disease, a disorder of platelet function with labile factor VIII. Lupus anticoagulants, which are autoantibodies, can also prolong APTT times in the presence of an increased risk of thrombosis.
  • Factor deficiencies: A deficiency in clotting factors XI or XII may also lead to an increase in APTT values. These deficiencies are usually identified in screening tests for coagulation profile.
  • Liver Disease, Vitamin K Deficiency, or DIC: APTT can be utilized in conjunction with other tests, such as PT, to diagnose diseases like liver disease, vitamin K deficiency, or DIC. All these conditions of the system involve multiple clotting factors and necessitate immediate medical care.

APTT Test vs PT Test

When physicians test for blood clotting function, they will frequently put both the APTT vs PT on an extended coagulation profile. Even though they are both ordered to accomplish about the same thing, they are testing different parts of the clotting cascade.

APTT test or Activated Partial Thromboplastin Time is a test that checks the intrinsic and common pathways of coagulation. It is optimum for diagnosing Hemophilia, postheparin therapy, and in the diagnosis of blood clotting disorders. PT test is utilized in the determination of extrinsic and common pathways and in the monitoring of warfarin therapy and the diagnosis of liver disease and vitamin K deficiency.

If both are requested at once, APTT vs PT provides some general indication of a patient's capacity to clot blood. If both APTT and PT reports are abnormal, there could be some evidence of generalized coagulation defect. APTT vs PT comparisons result enables physicians to diagnose some deficiencies or disorders of the cascade of coagulation more precisely.

APTT Test Price in Pakistan

The APTT test cost may differ from one healthcare facility to another, from city to city, and even if it is combined with the examination of nerve conduction or not. A patient must pay around PKR 7,000 to PKR 15,000 for the complete procedure of the APTT test on average. High-tech facilities may be slightly more depending upon how severe the test would be and how experienced the expert is.

Observe that all these prices would normally encompass the whole EMG testing process, neurologist APTT test interpretation, and even a follow-up visit with the doc sometimes. The labs are able to offer packages where both blood coagulation studies, such as an APTT, are part of it in case muscle or nerve symptoms are presumed to be secondary to the abnormalities of the coagulation profile.

At the right price, it has to be reserved in advance. All the private labs provide details of the cost of the APTT test in Pakistan on the site or from the lab's online portal.

Book lab tests from the best-certified labs in Lahore, Karachi, Islamabad, and all major cities of Pakistan through InstaCare, and get a discount of up to 35%. For assistance, call our helpline at 03171777509 to find the right lab test for your health needs.