# Review the warfarin monitoring trend.

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=568342&lang=en  
> language: en  
> subject: Medication Administration  
> category: PPT

## Question

Review the warfarin monitoring trend.

| Time | Data |
| --- | --- |
| Day 1 | INR: 2.4; warfarin dose: 5 mg; notes: Baseline, no bleeding |
| Day 3 | INR: 3.1; warfarin dose: 5 mg; notes: Started TMP-SMX |
| Day 5 | INR: 4.2; warfarin dose: 5 mg; notes: TMP-SMX completed |
| Day 7 | INR: 5.8; warfarin dose: 5 mg; notes: New bruising, black tarry stools |

Q1. What is the most likely cause of the INR elevation?

The client developed warfarin resistance
TMP-SMX inhibited warfarin metabolism
The client increased vitamin K intake
The client missed a warfarin dose

Q2. Which finding is the most concerning for active bleeding?

INR of 5.8
New bruising
Black tarry stools
Recent antibiotic use

Q3. What is the priority nursing action?

Administer the scheduled warfarin dose
Reduce the warfarin dose by half and recheck INR in 2 days
Give oral vitamin K and resume warfarin tomorrow
Hold warfarin and notify the provider

## Explanation

The INR trend shows a progressive rise from 2.4 to 5.8 after TMP-SMX initiation, with new bruising and melena. This indicates a significant drug interaction causing supratherapeutic anticoagulation and possible gastrointestinal bleeding. The nurse must hold warfarin and notify the provider immediately.

## In-depth explanation

Quick answer
Hold warfarin and notify the provider immediately.

Why this is correct
INR 5.8 with melena and bruising indicates supratherapeutic anticoagulation with active bleeding risk. Warfarin must be held and the provider notified for urgent management.

Clinical picture
TMP-SMX inhibits warfarin metabolism, causing INR elevation. Melena suggests upper GI bleeding, requiring immediate intervention.

Memory hook
INR >5 with bleeding signs: hold warfarin, notify provider, consider vitamin K.

NCLEX decision rule
Never administer warfarin when serious bleeding is suspected.

Why the alternatives are wrong
Reducing the dose or waiting to recheck INR delays needed intervention and risks further bleeding.

Sources
1NCSBN 2026 NCLEX-RN Test Plan
2DailyMed Warfarin Search

## Clinical scenario

A 68-year-old client with atrial fibrillation is managed with warfarin. The client reports new easy bruising and dark, tarry stools. The client recently completed a 5-day course of trimethoprim-sulfamethoxazole (TMP-SMX) for a urinary tract infection. The nurse reviews the following data.

## Key concepts

- **TMP-SMX** — Trimethoprim-sulfamethoxazole, an antibiotic that inhibits warfarin metabolism, increasing INR and bleeding risk.
- **Melena** — Black, tarry stools caused by digested blood, indicating upper gastrointestinal bleeding.
- **INR** — International Normalized Ratio, a measure of warfarin's anticoagulant effect; therapeutic range typically 2.0-3.0 for atrial fibrillation.

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