THIOPURINE METHYLTRANSFERASE (TPMT), ERYTHROCYTES
Marquette General Health System

General Info

Alpha Code

   TPMT

MGH LIS Test No

   9194

Schedule

   Monday, Wednesday, Friday

Testing Time

   2 days

Testing Lab

   Mayo Labs

QORR Test Code

   TPMT

Specimen Info

Type

      

Volume

    

Temperature

   Refrigerate

Preservative

    

Collection Info

   Draw blood in green-top (heparin) tube(s), and send 5.0 mL of 
heparinized whole blood refrigerated. (Keep specimen cool with frozen
coolant April-October. Protect specimen from freezing by placing it in 
a bubble-pack bag [Supply T055] supplied by Mayo Medical Laboratories.
Use refrigerated coolant November-March).
NOTE:  SPECIMEN MUST ARRIVE AT MML WITHIN 72 HOURS OF COLLECTION.      
 
Specimen Acceptability

Methods
Enzymatic End Point Useful for detection of individuals with low thiopurine methyltransferase who have excessive myelosuppression when taking azathioprine (Imuran) and 6-mercaptopurine (6-MP) (Purinethol).

Clinical Utilities

CPT Codes
83789

Reference Range
15.1-26.4 U/mL RBC (normal)
6.3-15.0 U/mL RBC (heterozygous for low TPMT)
<6.3 U/mL RBC (homozygous for low TPMT)      

Component Information

Collection Notes

Additional Comments

 

Questions or Comments email support@mgh.org

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