TPMT

Alternative names, keywords

Thiopurine methyltransferase

Samples required

EDTA blood (purple cap/ yellow cap ring, 4 mL tube).

Misleading results may be obtained if patient has had a recent red blood cell transfusion.

Test indications

To be used before starting azathioprine to test for idiotypic sensitivity.

Patients already on azathioprine or mercaptopurine may have increased activity due to induction of TPMT.

Reference range

Whole blood TPMT activity in mU/L:

Turnaround time

Referral lab quotes turnaround time of 5 days, however additional time must be allowed for packing, dispatch and delivery of sample, and return and processing of results.

Enquiries

Biochemistry (Referrals)