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Chemistry & Basic Tests
PT/INR (Prothrombin Time)
Measures blood clotting time. Used to monitor warfarin therapy and assess bleeding disorders.
CPT code
85610
Turnaround time
24–72 hours
Fasting required
No fasting needed
Collection container
Light Blue Top (Citrate)
About this test
Measures blood clotting time. Used to monitor warfarin therapy and assess bleeding disorders.
Specimen requirements
Collection container
Light Blue Top (Citrate)
blue top
Specimen
Plasma
How to prepare
- 1
Bring a valid photo ID to your appointment
- 2
Plan for a 15–30 minute visit
Special instructions
Collect blood in a blue-top tube with 3.2% sodium citrate, filling the tube completely to maintain the correct ratio. Gently invert at least 6 times immediately after collection.