Laboratory Test Information Guide

Details for Thiopurine Methyltransferase: Phenotype

Test Name: Thiopurine Methyltransferase: Phenotype
Alternate Name(s): TPMT Phenotype
Laboratory: Core
Specimen Type: 4 mL Lavender EDTA Vacutainer tube
Collection Information: A minimum volume of 1 mL is required for testing.

Avoid gel-separator tubes. Do not freeze, store and send cold.

Note: This test is only available to gastroenterologists at SJH/LHSC. If requested by other physicians approval must be given by the Biochemist on-call.
Requisition: GENERAL LABORATORY REQUISITION
Test Schedule: Referred out Monday-Thursday
Turnaround time from when specimen
is received in testing laboratory:
 
Routine
7 days
Stat
N/A
 
Reference Range: Low Activity: < 10 nmol/Hbh
Intermediate: 10 - 40 nmol/Hbh
Normal Activity: > 40 nmol/Hbh
Effective Date: 2015-08-25
Revised Date: 2020-06-22
Critical Value:  
Interpretive Comments: Falsely low TPMT activity is observed in patients being treated with aminosalicylates. Red blood cell transfusion pre-test may produce false indication of patient's TPMT status. Patients should be tested prior to Azathioprine or 6-MP treatment.
Special Processing:  
Comments:  
Method of Analysis: UPLC/Fluorescence
Critical Information Required:  
Storage & Shipment: Do not freeze. Please send on ice packs. Specimen must be received at ICL Monday-Thursday within 4 days of collection. State collection date. TPMT Genotyping is also available - see separate listing.
System Codes: 
Cerner
TPMTP
 
Referred To: In-Common Laboratories

Questions? Comments? Contact Laura Gopaul