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Warfarin Genotype (Prothrombin Gene Mutation Analysis)

Published: August 9, 2026Updated: August 16, 2026

This test checks for specific genetic variations in the prothrombin gene that may affect how your body processes warfarin, a blood thinner.

Quick summary

["Genetic variations can influence your dose needs for blood-thinning medication."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
93196-4
Short code
Warfarin genotype pnl Bld/T
Synonyms
Warfarin genotype pnl Bld/T
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
CPT
86430
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters for You

Warfarin is a medication used to prevent blood clots, but its effectiveness can vary widely among people due to genetic differences. This test helps healthcare providers determine the best starting dose for you, reducing the risk of bleeding or clotting.

What to Expect Before the Test

No special preparation is needed. You’ll provide a small blood sample, similar to other routine blood tests. The sample is collected by a healthcare professional in a clinic or lab.

How the Test Works

The test analyzes your DNA to identify specific mutations in the prothrombin gene (also called *F2 gene*). These mutations can alter how your body processes warfarin, which may require adjustments in dosage to maintain safe blood-thinning levels.

What the Results Mean

Results identify whether you carry certain genetic variants linked to warfarin metabolism. These findings help your doctor personalize your warfarin dose to balance safety and effectiveness, reducing the risk of complications like excessive bleeding or inadequate clot prevention.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Warfarin Genotype

Frequently asked questions

Does this test affect my warfarin dose immediately?
No, this test provides genetic information that helps your doctor adjust your warfarin dose over time. You’ll likely need regular blood tests (INR checks) to monitor your dose until your doctor confirms the best level for you.
How long does it take to get results?
Results are typically available within 1–2 weeks after the blood sample is collected. Your doctor will discuss the findings with you during your follow-up visit.
Can I stop taking warfarin while waiting for results?
No, it’s important to continue taking warfarin as prescribed. Genetic testing helps guide your dose but doesn’t replace regular monitoring. Always follow your doctor’s instructions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy