Partial thromboplastin time (PTT)APTT; PTT; Activated partial thromboplastin time
Partial thromboplastin time (PTT) is a blood test that looks at how long it takes for blood to clot. It can help tell if you have a bleeding problem or if your blood does not clot properly.
A related blood test is prothrombin time (PT).
Chernecky CC, Berger BJ. Activated partial thromboplastin substitution test - diagnostic. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:101-103.
Ortel TL. Antithrombotic therapy. McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 42.