247SimpleTests
NCLEX · Pharmacological Therapies

A client is prescribed warfarin (Coumadin). Which laboratory value monitors the therapeutic effect of this medication?

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

INR (International Normalized Ratio) — the standardized measure of prothrombin time used to monitor warfarin; therapeutic range is typically 2.0-3.0 for most indications (2.5-3.5 for mechanical heart valves)

  1. A aPTT
  2. B Platelet count
  3. C INR (International Normalized Ratio) — the standardized measure of prothrombin time used to monitor warfarin; therapeutic range is typically 2.0-3.0 for most indications (2.5-3.5 for mechanical heart valves)
  4. D Serum potassium

Why this is the answer

Warfarin monitoring: INR (International Normalized Ratio) is the standardized PT measurement for warfarin.

Therapeutic ranges: Most indications (atrial fibrillation, DVT/PE treatment): 2.0-3.0; Mechanical heart valves: 2.5-3.5.

INR above range: Excessive anticoagulation, bleeding risk — hold warfarin, possible vitamin K (antidote).

INR below range: Insufficient anticoagulation, clot risk.

Patient education: Maintain consistent vitamin K intake (don't suddenly increase/decrease leafy greens — vitamin K antagonizes warfarin); avoid alcohol; report signs of bleeding; many drug interactions.

Contrast: aPTT monitors HEPARIN (not warfarin); platelet count monitors for thrombocytopenia. The classic NCLEX confusion is warfarin/INR vs heparin/aPTT — memorize: 'WARfarin = INR; heparin = PTT.'.

Source: NCLEX-PN Physiological — Pharmacology, Warfarin INR

Practice more questions

This question is from our NCLEX Practice Tests practice test. Take the full practice test to test your knowledge across all Pharmacological Therapies and other topics.

Take the PN: Physiological Integrity practice test →

About this topic: Pharmacological Therapies

Pharmacological therapies questions cover medication administration, dosage calculation, the rights of medication administration, common drug classes and their side effects, and when to hold a medication and report. This is one of 18 PN: 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.

Related questions

Pharmacological Therapies

A client is prescribed digoxin (Lanoxin) for heart failure. What should the nurse assess BEFORE administering each dose?

 Pharmacological Therapies

A client is receiving IV heparin for deep vein thrombosis. Which laboratory value should the nurse monitor to assess therapeutic effectiveness?

 Pharmacological Therapies

A client is prescribed metformin (Glucophage) for type 2 diabetes. Which instruction is MOST important to include in client teaching?

 Pharmacological Therapies

A client is receiving IV morphine for pain. Which assessment finding requires the MOST IMMEDIATE intervention?

State-specific guides

Need information for your state? Our state guides cover local requirements, fees, and what to expect on exam day.

California Texas Florida New York Pennsylvania Illinois Ohio Georgia

Recommended study materials

Study guide

Saunders Comprehensive Review for NCLEX-RN 9th Ed. (Elsevier)

The gold standard for NCLEX-RN prep: 5,200+ practice questions, content review, test-taking strategy.

Check Price → Study guide

NCLEX-PN Prep Plus (Kaplan)

Targeted NCLEX-PN content review with hundreds of practice questions and video explanations.

Check Price → Study guide

Prioritization, Delegation & Assignment (Elsevier)

The leading resource for NCLEX questions on prioritization, delegation, and management of care.

Check Price →

As an Amazon Associate, CJ Affiliate, and AWIN publisher we earn from qualifying purchases. Links above are affiliate links. Full disclosure →