TPMT Genotyping
Ordering Recommendation
Use this genotyping test to assess genetic risk for severe myelosuppression with standard dosing of thiopurine drugs in individuals for whom thiopurine therapy is being considered or who have had an adverse reaction to thiopurine therapy. This test may be performed irrespective of whether thiopurine therapy is currently being administered.
For enzyme phenotyping prior to thiopurine treatment, refer to Thiopurine Methyltransferase, RBC (0092066). For thiopurine dosing optimization, refer to Thiopurine Metabolites in Red Blood Cells (3016503).
New York DOH Approval Status
Specimen Required
Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Refrigerated
Plasma or serum; specimens collected in sodium heparin or lithium heparin; frozen specimens in glass collection tubes; frozen yellow (ACD solution A or B)
Room temperature: 72 hours; Refrigerated: 1 week; Frozen: 1 month
Methodology
Polymerase Chain Reaction (PCR)/Flourescence Monitoring
Performed
Varies
Reported
5-10 days
Reference Interval
By report
Interpretive Data
Refer to report.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
Laboratory Developed Test (LDT)
Note
Whole blood is the preferred specimen. Saliva samples that yield inadequate DNA quality and/or quantity will be reported as inconclusive if test performance does not meet laboratory-determined criteria for reporting.
Hotline History
Hotline History
CPT Codes
81335
Components
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
2012238 | TPMT Genotype Specimen | 31208-2 |
2012239 | TPMT Genotype | 41048-0 |
2012240 | TPMT Predicted Phenotype | 36922-3 |
3017393 | TPMT Interpretation | 71356-0 |
3017394 | EER TPMT | 11526-1 |
Aliases
- 6-mercaptopurine
- 6-MP
- 6-TG
- 6-thioguanine
- AZA toxicity
- Azathioprine
- nucleoside diphosphate linked moiety X
- S-adenosyl-L-methionine genotype
- Thioguanine
- Thiopurine
- Thiopurine S-methyltransferase genotype
- TPMT genetics
- TPMT mutation