Lab Values & Diagnostics
Coagulation Studies (PT/INR/PTT)
Diagnostic tests used to evaluate the extrinsic and intrinsic pathways of the coagulation cascade.
Test Reference Ranges
- PT: 11–13.5 seconds
- INR: 0.8–1.1 (Therapeutic range 2.0–3.0 for warfarin therapy)
- PTT: 25–35 seconds (Therapeutic range 1.5–2.5x baseline for heparin)
Nursing Priorities
- Monitor for bleeding: hematuria, melena, or ecchymosis
- Ensure vitamin K is available as an antidote for warfarin
- Verify PTT during heparin infusion titration
- Hold doses and notify provider for supratherapeutic values
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