INR
CoagulationNormal range
0.8–1.1 (no anticoagulant) · therapeutic on warfarin: usually 2.0–3.0 (2.5–3.5 mechanical valve)
Critical high: > 5
☎ When to call
INR > 5, any INR with active bleeding, or a supratherapeutic INR before a procedure — call before the next dose. New neuro changes on warfarin = possible head bleed, escalate as emergency.
What you do
- Check the INR BEFORE giving today's warfarin — every time
- > 4–5: hold warfarin and clarify; bleeding assessment head-to-toe (gums, urine, stool, neuro)
- Know the reversal: vitamin K, and 4-factor PCC/FFP for serious bleeding
- New antibiotic on a warfarin patient = expect the INR to move
Causes of HIGH inr
Causes of LOW inr
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.; CHEST guidelinesReference only — verify against your facility's policy.
