Test directory: TPMT Activity Profile, Erythrocytes

Ordering Code 7924
Test Name TPMT Activity Profile, Erythrocytes
Alias Thiopurine Methyltransferase Activity Profile,
Erythrocytes
TPMT RBC
TPMT Enzyme
Preferred Specimen Whole Blood
Preferred Container EDTA, K2 (Lavender) 6 mL
Other Specimen/Container Whole Blood in Lithium Heparin (Green), Whole Blood in
Sodium Heparin (Green)
Optimum Volume 5 mL
Collection Instructions Patients should abstain from the following drugs for at least 48 hours prior to TPMT testing: Naproxen (Aleve),
Ibuprofen (Advil, Motrin), Ketoprofen (Orudis), Furosemide (Lasix), Sulfasalazine (Azulfidine), Mesalamine (Asacol),
Olsalazine (Dipentum), Mefenamic acid (Ponstel),
Trimethoprim (Proloprim), Methotrexate, Thiazide diuretics, and Benzoic acid inhibitors.
Transport Requirements Oahu: Ambient
Airline: Refrigerated
Specimen Stability Ambient: 6 Days
Refrigerated: 6 Days
Frozen: Not Stable
Rejection Criteria Grossly hemolyzed
Avail. Stat NO
Analytic Time 6 Days
Methodology Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Reference Lab  Mayo Medical Lab

Reference range(s)

The reference ranges listed below are valid on this date of June 29, 2025.
Component Age Male Norm Male Critical Low Male Critical High Female Norm Female Critical High Female Critical Low Units Add'l info
Interpretation ALL See report.
6-Methylmercaptopurine ALL See report.
6-Methylmercaptopurine riboside ALL See report.
6-Methylthioguanine riboside ALL See report.
Reviewed By ALL See report.