Quest Diagnostics Prothrombin Time with INR (PT INR) Test
Type
Blood Testing
Biomarkers
1
Duration
30 min
Results
24 hours
Blood test measuring blood clotting time, monitoring warfarin therapy, and detecting bleeding or clotting disorders.
This test measures how long it takes for your blood to clot. It's used to monitor warfarin therapy (a blood thinner) in patients taking this medication to treat or prevent blood clots. The test can also help detect bleeding or clotting disorders. Results are presented as an INR (International Normalized Ratio), a standardized value consistent across labs. Abnormal results may indicate a need for medication adjustment or further investigation.
Key Details
- Biomarkers
- 3–6 clotting markers
- Fasting Required
- No
- Sample Type
- Blood draw
- Turnaround
- Same day to 24 hours
- Common Use
- Anticoagulant monitoring, clotting disorder screening
Who Is This For?
People taking blood-thinning medications (warfarin, heparin) who need regular monitoring. Anyone with unexplained bruising, prolonged bleeding, or a history of blood clots. Women with recurrent miscarriages, which can be caused by clotting disorders. People with a family history of deep vein thrombosis (DVT) or pulmonary embolism.
What's Included
Preparation Required
Fasting for 10–12 hours before your appointment is recommended for accurate results (water is fine). Avoid alcohol for 24 hours and intense exercise for 12 hours before the blood draw. Morning appointments are ideal for consistent hormone and glucose readings. The blood draw typically takes 5–10 minutes.
Biomarkers Tested
1Activated partial thromboplastin time ratio — measures how long it takes blood to clot through the intrinsic pathway. Used to monitor heparin therapy and detect clotting factor deficiencies or lupus anticoagulant.
+ $6.00 Physician Service Fee
- Category
- Diagnostic
- Sample Type
- Blood draw
- Duration
- 30 min
- Results
- 24 hours