Test Directory

• DPYD Genotype
• DPYD Metabolic Activity
• DPYD Information

The dihydropyrimidine dehydrogenase gene (DPYD) produces a drug-metabolizing enzyme, dihydropyrimidine dehydrogenase (DPD), which is involved in the metabolism of several clinically important drugs including the fluoropyrimidines 5-fluorouracil and capecitabine, which are frequently used as chemotherapeutic drugs. Individuals with some variant DPYD alleles are at increased risk for side effects from drugs that are metabolized by DPD. DPYD genotype information can be utilized to predict DPD metabolic activity, which can be used as an aid in determining a therapeutic strategy for drugs that are metabolized by DPD. For example, DPD eliminates over 80% of the drug 5-fluoracil. An intermediate or poor metabolizer may be subjected to a buildup of 5-fluoracil, which can be associated with severe toxicity. Substantial evidence supports the use of DPYD genotyping for guiding fluoropyrimidine dosage/use.

Specimen Type: Whole Blood

Alternate Specimen Type: Buccal Swab

Collection Container: Lavender Top (EDTA)

Alternate Collection Container: Pale Yellow Top (ACD) or LabCorp Buccal Swab Kit

Desired Specimen Volume: 2 mL whole blood or 4 buccal swabs

Whole Blood:

1. Collect a lavender top (EDTA) tube via venipuncture.

Buccal Swab:

1. Collect 4 buccal swabs following the instructions provided in the LabCorp buccal swab kit.

Whole Blood:

1. Transport 2 mL of whole blood in the original collection container.

Buccal Swab

1. Transport buccal swabs with materials provided in LabCorp buccal swab kit at room temperature.

Transport to the laboratory at room temperature. 

• Quantity not sufficient for analysis
• Improper container
• Single buccal swab
• Wet buccal swab
• Buccal swabs without outer collection envelope
• Severely damaged buccal swab envelope
• Buccal swab envelope received open
• Frozen glass tube

See patient report.

The exact effect of a particular genotype on individual drugs can vary. In addition to genotype, the metabolism of drugs may be influenced by additional factors that include environmental, dietary and other medications; these factors and others should be considered prior to initialing a new therapy. All results must be interpreted in the context of other test results and clinical findings. Results do not rule out the possibility of other variant alleles in DPYD or other variant alleles in other drug metabolism pathways. Patients should speak with their health care provider about the individual results of this test.

Molecular-based testing is highly accurate, but as in any laboratory test, rare diagnostic errors may occur.

• Dihydropyrimidine Dehydrogenase