Partial Thromboplastin Time, Activated (PTT) Test
The PTT test, also known as activated partial thromboplastin time or APTT, measures how long it takes a blood sample to clot through the intrinsic and common coagulation pathways. It is used as a screening test for deficiencies or inhibitors affecting the coagulation factors in those pathways.
About this test
Partial thromboplastin time, activated (PTT), also called APTT, measures the time it takes a blood sample to clot once factors in the intrinsic pathway (factors VIII, IX, XI and XII) and the common pathway (factors II, V, X and fibrinogen) are activated. The test uses photo-optical clot detection on a sample collected in a sodium citrate tube.
PTT is used as a screening test to detect deficiencies or inhibitors of the intrinsic and common pathway coagulation factors. A result outside what a clinician expects prompts further evaluation of which specific factor may be involved, rather than answering that question on its own.
Test details
| Quest code | 763 |
|---|---|
| Methodology | Photo-Optical Clot Detection |
| Sample type | One full unopened 3.2% sodium citrate (light blue-top) tube |
| Collection | Quest patient service center |
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Additional details
What this test looks at
The test reports a single measurement: the time in seconds it takes a blood sample to clot once factors in the intrinsic and common coagulation pathways are activated. Quest lists the test under the aliases APTT and PTT, which refer to the same measurement. It uses photo-optical clot detection performed on a sample collected in a sodium citrate (light blue-top) tube.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does the PTT test measure?
It measures the time it takes a blood sample to clot once factors in the intrinsic and common coagulation pathways are activated, using photo-optical clot detection.
How is the sample collected?
Through a blood draw collected into a sodium citrate (light blue-top) tube.
Do I need to prepare for this test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.
Is PTT the same as APTT?
Yes. Quest lists this test under the aliases APTT and PTT; both refer to the same measurement of partial thromboplastin time, activated.
How much is a PTT test?
$35, paid once at checkout. The price includes the physician's order this test requires and sample collection at a Quest patient service center.