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Dihydropyrimidine Dehydrogenase Activity in Plasma

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

This test measures the activity level of an enzyme called dihydropyrimidine dehydrogenase (DPYD) in your blood plasma. DPYD plays a key role in breaking down certain medications, including some chemotherapy drugs.

Quick summary

["This test helps assess how your body processes specific medications and may be used to personalize treatment plans for certain cancer therapies."]

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

Key facts at a glance

LOINC
104172-2
Short code
DPYD gene.c.1236G>A Geno Bld/T
Synonyms
DPYD gene.c.1236G>A Geno 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 Is This Test Done?

Your healthcare provider may order this test if you’re about to start a chemotherapy treatment that relies on DPYD for metabolism. It helps identify whether you’re at higher risk for side effects like severe nausea, diarrhea, or skin reactions, depending on the medication.

What Does the Test Measure?

The test measures how effectively your body’s DPYD enzyme works to process certain drugs. Lower-than-expected activity might mean your body processes these drugs differently, potentially increasing side effects or requiring dose adjustments.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The plasma portion is then analyzed for DPYD enzyme activity using a specialized laboratory method.

What Are Possible Results?

Results are typically reported as a ratio or activity level compared to a standard. Your provider will interpret the results in the context of your medication and overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is primarily used to guide chemotherapy dosing in patients who are at higher genetic risk for adverse reactions to certain drugs. For example, low DPYD activity is linked to increased risk of toxicity with drugs like 5-fluorouracil (5-FU) or capecitabine. Adjustments to dosage or alternative medications may be recommended based on the results.

Short name

DPYD Activity

Frequently asked questions

Why might my doctor recommend this test before starting chemotherapy?
Your doctor may recommend this test if you have a family history of severe side effects from chemotherapy drugs that rely on DPYD, or if you have certain genetic markers linked to lower enzyme activity. It helps ensure your treatment is as safe and effective as possible.
What if my DPYD activity test comes back lower than expected?
If your results suggest lower-than-normal DPYD activity, your doctor may adjust your chemotherapy dose or choose a different medication that doesn’t rely on this enzyme. They’ll work with you to manage risks while still delivering the most effective treatment.
Do I need to prepare for this test in any special way?
No special preparation is needed, but avoid eating or drinking anything (except water) for a few hours before your blood draw, as this may affect test results. Follow your healthcare provider’s specific 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