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Test ID LBOR0150 TPMT Genotyping

Important Note

This test is rarely covered by insurance.  A Patient Acknowledgement Form for Pharmacogenomics Services is required to accompany the specimen for all Medicare and non-Medicare patients.  In addition, for Medicare patients an ABN Form should also be submitted.  In the absence of the appropriate signed form(s), the ordering provider/facility will be billed. 

For patients with Blue Cross Blue Shield of North Dakota coverage, a separate completed and signed Advance Member Notice is required to accompany the specimen

 

Note:  Testing results may be delayed due to nation-wide supply challenges due to the COVID pandemic.  Current expected TAT is 7-10 days.  .

AKA

Azathioprine, Mercaptopurine, Thioguanine

Additional Information

See Thiopurine S-Methyltransferase (TPMT) Genotyping for additional information.

Specimen Type/Requirements

Lavender top (EDTA) tube -  Whole Blood 

 

Blood samples will not be accepted for patients that have undergone an allogenic transplant (e.g. bone marrow or peripheral stem cell) OR that have a history of chronic lymphocytic leukemia (CLL).

 

Transfusion patients:  Wait at least 2 weeks after a packed cell/platelet transfusion, and at least 4 weeks after a whole blood transfusion prior to blood draw for testing.

 

Chemotherapy patients:  DNA quality may be affected if patient has received chemotherapy within the last 120 days.  Clients will be contacted to provide additional specimen if DNA quality is insufficient.

 

All specimens should be sent in original container and should not be aliquoted to another tube.

In addition, the specimen submitted should ONLY be used for this testing and should not be shared with any other testing that would utilize this specimen type.

 

Test is not affected by hemolysis or lipemia. 

Stability/Transport

Room Temperature   72 hours    
Refrigerated   7 days Preferred for transport  
Frozen   Not Acceptable     

 

Performed Test Frequency

Monday through Friday

Methodology

Allele-specific PCR

Performing Lab

Sanford Laboratories Sioux Falls

CPT

81335

Specimen Volume

Preferred Volume   2.0 - 4.0 mL  
Minimum Volume   1.0 mL

 

Report Available

5 – 7 days

Useful For

  • Identify patients who are at risk for abnormal drug metabolism and toxicity from thiopurine drugs metabolized by thiopurine-S-methyltransferase (TPMT), including but not limited to azathioprine, 6-mercaptopurine, and 6 – thioguanine. 
  • Identify genotypes shown to have a drug-gene variant.