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Coagulation Studies (PT/INR/aPTT) — NCLEX Cheat Sheet

Warfarin → INR; Heparin → aPTT

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👤 By the CinnaRN Clinical Content Team 🕐 Updated 2026-07-11 🏷️ Pharmacological Therapies 🔖 Free to read, print, and share

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Use this quick-reference guide to spot, treat, and prevent Coagulation Studies (PT/INR/aPTT) on the NCLEX. Keep it handy during review and on exam day!

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Values

Key numbers

PT 11-13.5 sec
INR 0.8-1.1 normal
aPTT 30-40 sec

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Warfarin

Key facts

Monitor PT/INR
Therapeutic INR 2-3
Antidote: vitamin K

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Heparin

Key facts

Monitor aPTT
Therapeutic 1.5-2.5x control
Antidote: protamine sulfate

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Report

Notify / act now

INR >4 → bleed risk
Bleeding, bruising, hematuria

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Quick Tip

INR standardizes the PT and is the primary value used to dose warfarin.

📖 Related Topics

Digoxin Toxicity Heparin Therapy Warfarin Therapy Acetaminophen Poisoning in Children

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