Abnormal aPTT/Prothrombin Time Reflexive Profile
Test Includes
Activated partial thromboplastin time (aPTT); dilute Russell's viper venom time (dRVVT); international normalized ratio (INR); pathologist interpretation; prothrombin time; thrombin time
Special Instructions
• If PT is abnormal (above normal reference interval), the test will reflex to PT mixing studies and factor VII activity.
• If aPTT is abnormal (above normal reference interval), the test will reflex to aPTT mixing studies, hexagonal phospholipid neutralization, factor XI activity, factor IX activity, and factor VIII activity.
• If TT is abnormal (above normal reference interval), the test will reflex to fibrinogen activity and fibrinogen antigen.
• If reflex testing is performed, concomitant CPT codes/charges will apply.
Expected Turnaround Time
3 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Citrated plasma, frozen
Volume
Three 1 mL platelet-poor frozen tubes
Container
Blue-top (sodium citrated) tubes
Collection
Plasma must be separated from cells within 45 minutes of venipuncture and centrifuged a second time before being placed in plastic transport tubes. Freeze within two hours and keep frozen until testing is performed. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Storage Instructions
Freeze.
Patient Preparation
Ideally the patient should not be on anticoagulant therapy. Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa and thrombin inhibitor therapies for about three days prior to testing.
Test Details
Methodology
See individual tests.