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Thiopurine Metabolites (TPMT) Enzyme

Additional Codes

LAB7831

Performing Laboratory

PROMETHEUS Laboratories Inc.

Methodology

PROMETHEUS TPMT Enzyme testing provides a quantitative analysis of a patient’s thiopurine methyltransferase (TPMT) enzyme activity level. Because each patient metabolizes thiopurines differently, the efficacy and toxicity of thiopurines can vary widely from patient to patient. Knowledge of the TPMT enzyme phenotype may reduce time of response, allow physicians to individualize dosing, identify patients in whom thiopurine therapy should be avoided and help reduce the risk of leukopenia.

Specimen Requirements

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 5 mL

Specimen Transport Temperature

Refrigerate 8 days/Ambient <24 hours OK/Frozen NO

Day(s) Test Set Up

Turnaround Time:

3 business days from date of receipt.

Reference Values

Normal TPMT Activity: >21.0 EU/mL

Intermediate TPMT Activity: 6.0-21.0 EU/mL

Low TPMT Activity: <6.0 EU/mL

Test Classification and CPT Coding

82657

82542