INR / Prothrombin Time Interpretation
Interprets INR (International Normalised Ratio) and PT (Prothrombin Time) in clinical context: anticoagulation, liver disease, coagulopathy.
Score interpretation
INR 0.8–1.1 = normal. For warfarin patients: sub-therapeutic (increase dose).
→ No anticoagulation: normal. Warfarin patients: check adherence, dose, interactions. Repeat INR in 1–2 weeks.
Elevated coagulation. For warfarin: below therapeutic range for most indications.
→ Investigate: liver disease, DIC, factor deficiency, drug interactions. Warfarin: increase dose by 10–15%.
Therapeutic for AF and VTE prophylaxis (target 2–3).
→ Continue warfarin dose. Next INR in 4–8 weeks if stable.
INR >3. Increased bleeding risk.
→ Hold or reduce warfarin. No active bleeding: observe, reduce dose by 10–20%. Minor bleed: hold warfarin, vitamin K 1–2 mg orally.
INR ≥4. Significant haemorrhage risk.
→ Hold warfarin. Active bleeding: IV vitamin K 5–10 mg + PCC (prothrombin complex concentrate) or FFP. No bleed: oral vitamin K 2–5 mg. Recheck INR in 24 hours.
Interpretation bands for the INR Interpretation. Apply clinical judgement and local guidance.
References
- Keeling D et al. The management of heparin-induced thrombocytopenia. Br J Haematol. 2006;133(3):259-269.
- BCSH. Guidelines on oral anticoagulation with warfarin. Br J Haematol. 2011;154(3):311-324.
Related
Curated clinical cross-links plus same-class fallbacks.
- Prothrombin Complex Concentrate (PCC) · Coagulation Factor Concentrate — Warfarin Reversal
- Warfarin · Anticoagulant
- Bivalirudin (PCI Anticoagulation) · Direct Thrombin Inhibitor / PCI
- Vasopressin / Terlipressin · Vasopressin Analogue — Vasodilatory Shock / Variceal Bleeding
- Bivalirudin · Anticoagulation
- Warfarin · Vitamin K Antagonist (Anticoagulant)
- Major Haemorrhage / Massive Transfusion · BCSH; RCOA; RCEM; RCS — BCSH Guidelines
- Anaemia Investigation · BSH / NICE
- Splenomegaly Workup · BSH; BMJ Best Practice
- Deep Vein Thrombosis Diagnosis and Treatment · NICE CG144 / NICE NG158
- Sickle Cell Crisis · BSH 2021 / BCSH
- Neutropenic Sepsis · NICE CG151 2012 / ESMO
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.