CPT/HCPCS
85610
Order Code
CA003
Turnaround Time
24 hours
Test Includes
INR
Specimen Requirements
Specimen Source
Plasma
Transport Container
(Specimen Container)
(Specimen Container)
Light Blue (Na-Citrate)
Preferred Specimens
Plasma
Minimum Volume (uL)
90% fill required
Collection Instructions
(Transport Temperature)
(Transport Temperature)
Transport at Room Temperature
Specimen Stability
| Temperature | Period |
|---|---|
| Room temperature | 48 hours (unspun) |
| Refrigerated | |
| Frozen | 14 days |
Test Details
Methodology
Prothrombin time reagent containing thromboplastin and calcium chloride is mixed with the patient plasma and the time to clot formation is measured photo-optically. The calcium chloride overcomes the citrate anticoagulant and allows the tissue factor in the thromboplastin to initiate coagulation. The prolongation of the clotting time correlates with the degree of deficiency or inhibition of the extrinsic pathway factors.
Clinical Significance
The prothrombin time is a coagulation screening test. It measures, as a whole, the activity of the coagulation factors II, V, VII, X and I.
Reference Ranges
12.6 – 14.5 sec
