Prolonged Activated Partial Thromboplastin Time (aPTT)
Also known as: Intrinsic Factors
Use
Diagnose patients suspected of having a bleeding disorder due to a coagulation deficiency
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. Refer to Coagulation Collection Procedures for directions.
Limitations
Patients on anticoagulant therapy may receive inconclusive results due to interference with the test. Tube improperly filled, improper labeling, clotted specimen, hemolysis, and thawed specimens may be causes for rejection, affecting the accuracy of results. The testing process may require adjustments in lab practices for high hematocrit levels in some patients.
Methodology
Immunoassay (Multiplex Protein Panel)
Biomarkers
LOINC Codes
- 3209-4
- 3187-2
- 3226-8
- 3232-6
- 34571-0
- 6303-2
- 75514-0
Result Turnaround Time
2-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
3 mL
Minimum Volume
2 mL
Container
Blue-top (sodium citrate) tubes
Collection Instructions
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to ensure a proper blood to anticoagulant ratio. Mix immediately by gentle inversion. Centrifuge for 10 minutes, remove 2/3 of the plasma, then centrifuge again and transfer the plasma to a Labcorp PP transpak frozen purple tube. Freeze immediately and maintain frozen until tested.
Patient Preparation
Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test.
Storage Instructions
Freeze.
Causes for Rejection
Tube improperly filled; improper labeling; clotted specimen; hemolysis; thawed specimen