| Test | Conventional | SI | Threshold |
|---|---|---|---|
| Activated Partial Thromboplastin Time (aPTT) | 25-35 seconds | 25-35 seconds | > 70 seconds (bleeding risk) |
| Bleeding Time | 2-7 minutes | 2-7 minutes | - |
| D-Dimer | < 0.5 (negative) µg/mL FEU | < 0.5 mg/L FEU | - |
| Fibrinogen | 200-400 mg/dL | 2-4 g/L | < 100 mg/dL (bleeding risk) |
| International Normalized Ratio (INR) | 0.8-1.1 (off anticoagulation) ratio | 0.8-1.1 ratio | > 5.0 (high spontaneous bleeding risk) |
| Prothrombin Time (PT) | 11-13.5 seconds | 11-13.5 seconds | > 30 seconds (marked bleeding risk) |
| Thrombin Time | 14-19 seconds | 14-19 seconds | - |
Panel
Coagulation Studies
PT/INR, aPTT, fibrinogen, and D-dimer for bleeding and clotting. 7 tests, 4 with a taught threshold.
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Frequently asked questions
What tests are in a Coagulation Studies?
The Coagulation Studies on this page lists 7 tests: Activated Partial Thromboplastin Time (aPTT), Bleeding Time, D-Dimer, Fibrinogen, International Normalized Ratio (INR), Prothrombin Time (PT), Thrombin Time. Each is shown with its conventional and SI teaching reference range.
What does the Coagulation Studies check for?
PT/INR, aPTT, fibrinogen, and D-dimer for bleeding and clotting. These are educational teaching values - ranges vary by laboratory and method, and are not for clinical decisions.
Which Coagulation Studies values are critical?
4 of the 7 tests in this Coagulation Studies carry a taught threshold: Activated Partial Thromboplastin Time (aPTT) (> 70 seconds (bleeding risk)); Fibrinogen (< 100 mg/dL (bleeding risk)); International Normalized Ratio (INR) (> 5.0 (high spontaneous bleeding risk)); Prothrombin Time (PT) (> 30 seconds (marked bleeding risk)). These are teaching thresholds, not clinical cutoffs - always use the values your laboratory reports.