✍️ Written by the MedTestBD Editorial Team · Last reviewed: July 2026
What is the APTT Test?
The APTT (Activated Partial Thromboplastin Time) test measures how long it takes for blood to clot through the intrinsic clotting pathway. It evaluates the function of clotting factors that are essential for normal blood coagulation. APTT is closely related to the PT/INR test but measures different clotting factors. Together, PT and APTT give a complete picture of a patient's clotting ability and are routinely ordered before surgery or to monitor anticoagulant therapy.
Why is the APTT Test Done?
- To monitor patients on heparin therapy — heparin works through the intrinsic pathway and prolongs APTT
- To investigate unexplained bleeding, bruising, or prolonged bleeding after cuts or surgery
- To diagnose clotting factor deficiencies such as haemophilia A (Factor VIII deficiency) and haemophilia B (Factor IX deficiency)
- To screen for antiphospholipid syndrome — an autoimmune condition causing abnormal clotting and recurrent miscarriage
- To evaluate liver disease, as the liver produces most clotting factors
- Routine pre-operative assessment alongside PT/INR
Normal APTT Levels
| Status | APTT Value |
|---|---|
| Normal | 25 – 35 seconds (varies by lab) |
| Therapeutic range (on heparin) | 60 – 100 seconds (1.5 – 2.5× normal) |
| Prolonged (abnormal) | Above 35 seconds without anticoagulants |
A prolonged APTT without anticoagulant therapy suggests a clotting factor deficiency, liver disease, or antiphospholipid antibodies. In patients on heparin, APTT is checked regularly — typically every 6 hours — to ensure the dose is within the therapeutic range. Too low risks clotting; too high risks bleeding.
How to Prepare for the APTT Test
- No fasting is required
- Inform your doctor about all anticoagulant medications you are taking — especially heparin, as APTT is used specifically to monitor heparin dosing
- Inform the doctor about any bleeding disorder, liver disease, or recent surgery
- The blood sample must be handled carefully and processed promptly — delays affect accuracy
- A blood sample is drawn from a vein in your arm into a special citrate tube
APTT Test Price in Bangladesh
APTT test prices vary between diagnostic centers across Bangladesh. Compare APTT test prices on MedTestBD →
⚠️ This information is for general reference only. Always consult a qualified physician before undergoing any medical test.
