Thiopurine Methyltransferase (TPMT), Enzyme Activity, Erythrocytes

TEST: 510750
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CPT: 82657
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Synonyms

TPMT Biochemical Assay Myelotoxicity

Special Instructions

>For New York state patients: Test orders for TPMT Enzyme Activity must include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form (Informed Consent for TPMT Enzyme Activity Test) in Related Documents.

Expected Turnaround Time

4 - 7 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Informed Consent For TMPT Enzyme Activity Test

    Specimen Requirements

    Specimen

    Whole blood

    Volume

    8 mL

    Minimum Volume

    5 mL (Note: This volume does not allow for repeat testing.)

    Container

    Lavender-top (EDTA) tube or green-top (sodium heparin) tube

    Storage Instructions

    Ship refrigerated.

    Causes for Rejection

    Frozen specimen, gross hemolysis

    Test Details

    Use

    Determination of TPMT levels that may be associated with toxicity of anticancer and anti-inflammatory drugs.

    Limitations

    For patients having an intrinsic low level of TPMT, recent RBC transfusion can variably increase their assayed enzymatic activity depending on the amount and circulating half-life of the transfused red blood cells. This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

    Methodology

    Enzymatic endpoint/liquid chromatography/tandem mass spectrometry (LC/MS-MS)