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NCLEX · Pharmacological Therapies

A client is prescribed warfarin (an anticoagulant). Which laboratory value is monitored to assess its therapeutic effect?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

Prothrombin time (PT) and INR (international normalized ratio)

  1. A Potassium level
  2. B Blood glucose
  3. C Prothrombin time (PT) and INR (international normalized ratio)
  4. D Hemoglobin A1C

Why this is the answer

WARFARIN (Coumadin) is monitored using PROTHROMBIN TIME (PT) and INR (international normalized ratio). NCLEX physiological/pharmacology. The therapeutic INR for most conditions is 2.0-3.0 (higher for some, e.g., mechanical heart valves). A too-high INR means increased bleeding risk; too-low means inadequate anticoagulation. The ANTIDOTE for warfarin is VITAMIN K.

Teaching: maintain consistent vitamin K intake (leafy greens) — don't suddenly change diet; watch for bleeding; many drug/food interactions.

Contrast: HEPARIN is monitored with aPTT (activated partial thromboplastin time); its antidote is protamine sulfate. Knowing warfarin → PT/INR (vitamin K antidote) and heparin → aPTT (protamine antidote) is a heavily tested NCLEX pharmacology pairing.

Source: NCLEX Physiological — Warfarin Monitoring (PT/INR)

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About this topic: Pharmacological Therapies

Pharmacological therapies questions cover medication administration and calculation, blood products, IV therapy, pain management, adverse effects and interactions, and the teaching that goes with high-alert drugs. This is one of 12 RN: Physiological Integrity questions on pharmacological therapies, each with a full explanation on a single study page.

New to this exam? Our NCLEX exam guide explains the format, scoring, and how to prepare.

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