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UGT1A1 Gene Mutation Screening (Blood)

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

This test checks for genetic variations in the UGT1A1 gene, which may affect how your body processes certain medications or bile acids.

Quick summary

A simple blood test to identify possible genetic differences linked to drug metabolism or bile flow issues.

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

Key facts at a glance

LOINC
41044-9
Short code
UGT1A1 gene Mut Anl Bld/T
Synonyms
UGT1A1 gene Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have a family history of conditions like Gilbert’s syndrome, bile duct obstructions, or certain drug reactions. It could also be used before starting medications that rely on UGT1A1 for metabolism, like irinotecan or some pain relievers.

What to Expect Before the Test

No special preparation is needed. You’ll have a small blood sample drawn from your arm, similar to other routine blood tests. The process takes about 5 minutes.

What the Results Mean

Results will show whether you carry specific mutations in the UGT1A1 gene. These variations can influence how your body processes medications or bile acids, which may affect symptoms like jaundice, fatigue, or drug effectiveness.

Common Conditions Linked to UGT1A1 Variations

Mutations in this gene may contribute to conditions like Gilbert’s syndrome (mild jaundice), bile duct disorders, or altered drug responses. Some people may also experience more severe reactions to certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

UGT1A1 mutations can impact how your liver processes drugs and bile acids. For example, certain mutations are strongly linked to severe side effects from chemotherapy drugs like irinotecan. They may also cause mild to moderate bile-related symptoms, such as fatigue or mild jaundice, depending on the variant.

Short name

UGT1A1 Mutation Test

Frequently asked questions

What does a positive result mean for my health?
A positive result indicates the presence of specific genetic variations in your UGT1A1 gene. These variations may affect how your body handles certain medications or bile acids, but they don’t necessarily mean you’ll develop a specific condition. Your healthcare provider will discuss how this may influence your treatment plan, especially if you’re taking medications that rely on this gene for metabolism.
Will this test affect my medication choices?
Possibly. Some medications, like chemotherapy drugs or certain pain relievers, may need dose adjustments if you have UGT1A1 mutations. Your doctor will review your results and adjust treatments accordingly to avoid side effects or ensure proper drug effectiveness.
Can I still get this test if I’m pregnant or breastfeeding?
Yes, this test can be performed during pregnancy or while breastfeeding. However, it’s important to discuss the potential implications with your healthcare provider, as some medications that rely on UGT1A1 metabolism may be avoided or adjusted during these times.
  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