Laboratory: Clinical Biochemistry
Test Name:
THIOPURINE METHYLTRANSFERASE (TPMT) GENOTYPING - (B)
Test Code: MISC
Clinical Information:
Blood is stable refrigerated (2-8°C) for up to 30 days.The recommended screening test for azathioprine and 6-mercaptopurine induced leucopenia is Thiopurine Methyltransferase Phenotyping (RBC) (test code:  TPMP).  Thiopurine Methyltransferase Genotyping is to be used as an alternative test when a patient has received multiple red blood cell transfusions prior to testing, and only tests for the more common mutations.  Thiopurine Methyltransferase Genotyping requires pre-approval by a Clinical Biochemist.
For more information see Prometheus Laboratories
Collection Devices:
Transport specimen to lab on ice (to prevent specimen from freezing, wrap specimen in paper towel and place on ice). Patients should be tested prior to azathioprine or 6-MP administration.
Specimen Required:
Blood: 6.0 mL
Referral:
Requisition:
Reference Values:
A descriptive report will be sent.
Availability:
Within 3 Weeks
Requires pre-approval by a Clinical Biochemist (except for Oncology requests).
See Also:
More Information:
DO NOT CENTRIFUGE.  DO NOT FREEZE.  Keep refrigerated until shipped.  Ship specimen with ice or frozen ice pack.  To prevent specimen from freezing, do not place specimen directly on ice. 
Referred to Prometheus Lab in San Diego, CA. Do not ship on Friday or weekends.  
XTPMG