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Prothrombin Time
Test CodeLAB320
Alias/See Also
Protime, Protime-INR, PT-INR
CPT Codes
85610
Preferred Specimen
2.7 ml (2.7 ml minimum) sodium citrate (blue) whole blood. Refer to Hemostasis/Thrombosis Specimens section for specimen collection instructions
Minimum Volume
1.0 ml (1.0 ml minimum) citrated platelet-poor plasma
Instructions
Full tube, no partial fills
Specimen Stability
Unspun : 12 hours room temp; Separated from cells: 2 hours room temp, 2 hours refrigerated, 1 week frozen
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis: >500mg/dL hemoglobin, Lipemia: >1000mg/dL, Bilirubin: >30mg/dL.
Methodology
Mechanical Clot Detection, Calculated
Setup Schedule
Mon- Sun
Reference Range
Normal range for PT – 9.4 – 12.5 seconds. Oral Anticoagulant Therapeutic Ranges:
INR 2.0-3.0 Venous thrombosis, pulmonary embolus, peripheral vascular disease.
INR 2.5-3.5 Mechanical prosthetic heart valves, recurrent thrombosis
Normal range for INR – 0.9 – 1.2
INR 2.0-3.0 Venous thrombosis, pulmonary embolus, peripheral vascular disease.
INR 2.5-3.5 Mechanical prosthetic heart valves, recurrent thrombosis
Normal range for INR – 0.9 – 1.2
Clinical Significance
The prothrombin time is a basic coagulation-screening test for the assessment of congenital and acquired
deficiencies of the extrinsic pathway (factors X, VII, V and II). The prothrombin time can be prolonged in certain
clinical states, i.e. warfarin therapy, intestinal reabsorption disorders, liver failure, fibrinolysis and DIC
deficiencies of the extrinsic pathway (factors X, VII, V and II). The prothrombin time can be prolonged in certain
clinical states, i.e. warfarin therapy, intestinal reabsorption disorders, liver failure, fibrinolysis and DIC
Performing Laboratory
Piedmont Athens Regional
