5-Fluorouracil (5FU) Toxicity Test
Short Name: 5FU Toxicity Test
Also known as: DPYD Gene Test, 5FU Sensitivity Test, Fluoropyrimidine Toxicity Test, Dihydropyrimidine Dehydrogenase Deficiency Test, DPYD Pharmacogenomics Test
5-Fluorouracil (5FU) Toxicity Test test available at DNA Labs India for ₹10,000. Uses PCR (Polymerase Chain Reaction), Sanger Sequencing, Next-Generation Sequencing (NGS) on Whole Blood (EDTA) samples. Results in Results are typically available within 1 week from the date of sample receipt at the laboratory. Reports are delivered via our secure online portal, email, and WhatsApp.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr SULOCHANA HEMCHANDRA HOLLA
Consultant Medical Geneticist · Reg: 8532
Last reviewed: September 7, 2026
Overview
The primary purpose of the 5FU Toxicity Test is to detect DPYD gene polymorphisms that cause partial or complete deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme. DPD deficiency leads to impaired metabolism of fluoropyrimidine drugs, resulting in drug accumulation and severe toxicities including myelosuppression, severe diarrhoea, mucositis, hand-foot syndrome, neurotoxicity, and in extreme cases, death. By identifying at-risk patients before the first chemotherapy cycle, oncologists can implement dose reductions (25-50%), extended intervals between cycles, or switch to non-fluoropyrimidine regimens, thereby improving patient safety and treatment outcomes.
- Test Code
- 51
- CPT Code
- 81225
- ICD Code
- Z15.01
- Price
- ₹10,000
- Sample Type
- Whole Blood (EDTA)
- Result Time
- Results are typically available within 1 week from the date of sample receipt at the laboratory. Reports are delivered via our secure online portal, email, and WhatsApp.
- Fasting Required
- No
- Method
- PCR (Polymerase Chain Reaction), Sanger Sequencing, Next-Generation Sequencing (NGS)
Sample Collection
No special preparation such as fasting is required. Ensure the Genomics Clinical Information Requisition Form (Form 20) is duly filled and signed before sample collection.
Method: Venipuncture
Laboratory Analysis
A standard venipuncture will be performed to collect 4 mL of whole blood into a Lavender Top (EDTA) tube. The procedure typically takes less than 5 minutes and is similar to a routine blood draw.
Report Delivery
Apply pressure to the puncture site with sterile cotton for 3-5 minutes to prevent bruising. No post-collection restrictions are necessary. The sample will be shipped refrigerated; do not freeze.
Timeline: Results are typically available within 1 week from the date of sample receipt at the laboratory. Reports are delivered via our secure online portal, email, and WhatsApp.
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of the 5FU Toxicity Test is to detect DPYD gene polymorphisms that cause partial or complete deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme. DPD deficiency leads to impaired metabolism of fluoropyrimidine drugs, resulting in drug accumulation and severe toxicities including myelosuppression, severe diarrhoea, mucositis, hand-foot syndrome, neurotoxicity, and in extreme cases, death. By identifying at-risk patients before the first chemotherapy cycle, oncologists can implement dose reductions (25-50%), extended intervals between cycles, or switch to non-fluoropyrimidine regimens, thereby improving patient safety and treatment outcomes.
How to Prepare
- Duly filled Genomics Clinical Information Requisition Form (Form 20) is mandatory
- Collect 4 mL (minimum 2 mL) whole blood in a Lavender Top (EDTA) tube
- Gently invert the tube 8-10 times to mix blood with EDTA anticoagulant
- Ship the sample refrigerated at 2-8°C; DO NOT FREEZE
- Label the tube clearly with patient name, date of collection, and sample ID
- Transport the sample to the laboratory within 6 hours of collection for optimal results
Doctor's Notes
Reviewed by Dr SULOCHANA HEMCHANDRA HOLLA — MBBS, MD (Medical Genetics) · Reg. No. 8532
"DPYD genotyping before initiating fluoropyrimidine-based chemotherapy is now recommended by multiple international oncology guidelines. Identifying patients who carry loss-of-function DPYD variants allows us to adjust 5FU or capecitabine doses preemptively, significantly reducing the risk of life-threatening toxicities such as severe myelosuppression, mucositis, diarrhoea, and neurotoxicity. I routinely order this test for every patient before their first cycle of 5FU or capecitabine to ensure the safest possible treatment plan."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Sample received frozen
- Insufficient sample volume (less than 2 mL)
- Clotted or haemolysed sample
- Missing or incomplete Genomics Clinical Information Requisition Form (Form 20)
- Unlabelled or mislabelled sample tube
- Sample collected in wrong tube type (non-EDTA)
Understanding Your Results
Normal Metaboliser (No pathogenic DPYD variants detected)
Patient has normal DPD enzyme activity. Standard doses of 5FU or capecitabine can be administered per protocol. Routine clinical monitoring during chemotherapy remains advisable.
Clinical action: Proceed with standard fluoropyrimidine dosing
Intermediate Metaboliser (One reduced-function variant detected)
Patient has approximately 50% reduced DPD activity. Increased risk of moderate to severe fluoropyrimidine toxicity including myelosuppression, diarrhoea, and mucositis.
Clinical action: Reduce initial 5FU or capecitabine dose by 25-50% as per EMA guidelines; monitor closely for toxicity
Poor Metaboliser (Two loss-of-function or reduced-function variants detected)
Patient has absent or severely reduced DPD enzyme activity. Extremely high risk of life-threatening fluoropyrimidine toxicity. Fluoropyrimidine drugs are contraindicated.
Clinical action: Avoid fluoropyrimidines entirely; select an alternative non-fluoropyrimidine chemotherapy regimen
Variant of Unknown Clinical Significance
A DPYD variant was detected but its functional impact on DPD enzyme activity has not been conclusively established in current literature. Clinical correlation and additional phenotypic testing may be warranted.
Clinical action: Consider uracil loading test or consult a clinical geneticist for further evaluation
Consult your oncologist immediately if you experience any of the following during or after fluoropyrimidine chemotherapy: severe diarrhoea (more than 4-6 episodes per day), mouth sores or ulceration that prevent eating or drinking, fever or signs of infection, unusual bruising or bleeding, numbness or tingling in hands or feet (peripheral neuropathy), or chest pain and difficulty breathing. If you have not yet started chemotherapy, discuss DPYD genotyping with your oncologist before the first cycle.
Limitations
- ⚠This test screens only for the most clinically validated DPYD variants; rare or novel variants may not be detected
- ⚠Results reflect germline genetic status only and do not account for somatic mutations in tumour DNA
- ⚠Phenotype predictions based on genotype may not perfectly correlate with actual DPD enzyme activity
- ⚠Environmental factors, hepatic function, and drug interactions may modulate 5FU toxicity independent of DPYD genotype
- ⚠This test does not replace clinical monitoring during chemotherapy; toxicity surveillance remains essential
Risks & Considerations
- ●Minimal risk associated with blood draw: minor bruising or discomfort at the puncture site
- ●Extremely rare risk of infection at the venipuncture site
- ●No genetic risk: this is a germline test and does not alter DNA
- ●Emotional impact: receiving information about genetic predisposition to drug toxicity may cause anxiety; genetic counselling is recommended
Interfering Factors
- ●Recent blood transfusion within the past 30 days may affect DNA quality
- ●Prior bone marrow transplant may yield donor DNA rather than patient DNA
- ●DNA degradation due to improper sample storage or delayed shipment
- ●Contamination of EDTA tube with other sample types
- ●Concurrent medications do not interfere with DNA-based genotyping
Compare With Similar Tests
| Test | 5-Fluorouracil (5FU) Toxicity Test | UGT1A1 Genotyping (Irinotecan Toxicity Test) | TPMT/NUDT15 Gene Test (Thiopurine Toxicity Test) | Comprehensive Pharmacogenomic Panel |
|---|---|---|---|---|
| Comparison | 5-Fluorouracil (5FU) Toxicity Test |
Frequently Asked Questions
What is the 5-Fluorouracil (5FU) Toxicity Test?
Why is DPYD gene testing important before starting chemotherapy?
Who should get the 5FU Toxicity Test?
How is the 5FU Toxicity Test performed?
Does the 5FU Toxicity Test require fasting?
How long does it take to get the 5FU Toxicity Test results?
What is the cost of the 5FU Toxicity Test in India?
Is the DPYD gene test a one-time test?
What happens if the test shows I am a poor metaboliser of 5FU?
Can I take the 5FU Toxicity Test if I have already started chemotherapy?
Is home sample collection available for the 5FU Toxicity Test?
What is the difference between the 5FU Toxicity Test and a Liver Function Test?
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