Test directory: TPMT Activity

Ordering Code 8563
Test Name TPMT Activity
Alias Thipurine Methyltransferase Activity
TPMT RBC
TPMT
Enzyme
Azathioprine Mercaptopurine Toxicity
Preferred Specimen Whole Blood
Preferred Container EDTA, K2 (Lavender)
Optimum Volume Two full tubes (3mL in each)
Collection Instructions Collect blood prior to azathioprine (Imuran) or 6-mercaptopurine (6-MP, Purinethol) therapy for screening purposes.
Transport Requirements Oahu: Refrigerated
Airline: Refrigerated
Specimen Stability Ambient: 48 Hours
Refrigerated: 9 Days
Frozen: Not Stable
Rejection Criteria Clotted, Hemolyzed, Forensic specimen
Avail. Stat NO
Analytic Time 10 Days
Methodology Chromatography/Mass Spectrometry
Reference Lab  Quest Diagnostic Lab-NI

Reference range(s)

The reference ranges listed below are valid on this date of May 22, 2026.
Component Age Male Norm Male Critical Low Male Critical High Female Norm Female Critical High Female Critical Low Units Add'l info
TPMT Activity ALL See report.