Test Overview
Test Usage

Phenotypic test that provides a quantitative measurement of TPMT enzyme activity levels to assist physicians with azathioprine (Imuran) or 6-MP (Purinethol) dosing strategies. Individuals with low thiopurine methyltransferase are at risk of excessive myelosuppression.

Reference Range *

Normal TPMT Activity: >21.0 EU/mL; Intermediate TPMT Activity: 6.0-21.0 EU/mL; Low TPMT Activity: <6.0 EU/mL.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Monday - Friday
Analytic Time

5 - 8 days

Soft Order Code
TPMTE
MiChart Code
TPMT Enzyme, Erythrocytes
Synonyms
  • Thiopurine Methyltransferase (TPMT), Phenotype
  • TPMT Enzyme
  • TPMTPHE
  • TPMT Phenotype
  • Thiopurine Methyltransferase (TPMT), Erythrocytes, Enzyme Activity
Laboratory
Sendout
Reference Laboratory
Prometheus 3320
Section
Special Testing
Specimen Requirements
Collection Instructions

Collect specimen in a lavender top tube. Refrigerate and send intact specimen within 5 days of collection. Do not freeze.

Lavender Top Tube
Normal Volume
5 mL EDTA whole blood
Minimum Volume
2 mL EDTA whole blood
Additional Information

Test sent to Prometheus Labs.

Billing
CPT Code
82657
Fee Code
36155
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