partial thromboplastin time

biochemistry

Also known as: PTT, activated partial thromboplastin time

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July 23, 2026

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The partial thromboplastin time (PTT) is a laboratory test used to assess the intrinsic pathway of blood coagulation. This pathway involves a series of proteins that interact on membrane surfaces to form a fibrin clot. The PTT test measures the time it takes for plasma to clot after adding specific reagents and calcium ions, typically between 25 to 50 seconds. A prolonged PTT can indicate a deficiency in one or more clotting factors or the presence of an inhibitor. This test is crucial for monitoring anticoagulant therapy and diagnosing bleeding disorders.1

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bleeding and blood clotting
Intrinsic pathway of blood coagulation
…simple laboratory test called the partial thromboplastin time (PTT), or, more accurately, the activated partial thromboplastin time. Plasma is collected and anticoagulated with citrate buffer; the citrate binds and effectively removes functional calcium ions from the plasma. Under these conditions, a fibrin clot cannot be generated. A negatively charged material,…
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…simple laboratory test called the partial thromboplastin time (PTT), or, more accurately, the activated partial thromboplastin time. Plasma is collected and anticoagulated with citrate buffer; the citrate binds and effectively removes functional calcium ions from the plasma. Under these conditions, a fibrin clot cannot be generated. A negatively charged material,…
Read More