Activated partial thromboplastin time (aPTT)

aPTT (Activated Partial Thromboplastin Time) - a laboratory test that determines the time required for a blood clot to form through the intrinsic and common pathways of the coagulation system.

It is used to assess the blood coagulation process, identify possible haemostasis disorders, and monitor unfractionated heparin therapy.

Indications

• Assessment of the blood coagulation system
• Suspected haemostasis disorders
• Tendency to bleed or frequent bruising
• Detection of a possible deficiency of coagulation factors
• Monitoring of unfractionated heparin therapy
• Preoperative assessment

Procedure

For the test, venous blood is collected into a special tube containing sodium citrate.

After collection, the clot formation time is determined following the addition of the reagents required for the test.

Test method

Coagulometric method, based on determining the clot formation time after activation of plasma with specific reagents.

Sources:

https://www.webmd.com/a-to-z-guides/partial-thromboplastin-time-test
https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=aptt
https://en.wikipedia.org/wiki/Partial_thromboplastin_time
https://myhematology.com/platelet-disorders/activated-partial-thromboplastin-time-aptt/
https://www.verywellhealth.com/pt-ptt-and-inr-results-3157005
https://www.ncbi.nlm.nih.gov/books/NBK507772/