Thiopurine Methyltransferase (TPMT) Genotype for Drug Metabolism

CPT Code(s):


Specimen Requirements:

Collect at least 3 mL of blood in a lavender-top tube (EDTA).

Specimen Preparation: Transport 3 mL of whole blood. (Minimum: 1 mL)

Storage/Transport Temperature: Refrigerated

Stability (collection to initiation of testing):

  • Ambient: 72 hours
  • Refrigerated: 1 week
  • Frozen: Unacceptable


Detection of polymorphisms within the TPMT gene associated TPMT deficiency.


Within 10 business days

Reference Values:

No allelic variants detected (*1/*1)


Monday - Friday

Interpretation Data:

Analytical Interpretation: The report includes the patient's diplotype of TPMT genes and is reported using star alleles as follows: