Table 9Stability of TPMT enzymatic activity

Storage temperatureSampleStorage time, anticoagulant study referenceStability
Room temperatureWhole blood24 h, heparin134
36 h, EDTA108
3 days, heparin121*
4 days, heparin127
5 days, heparin118
6 days, EDTA124
7 days, heparin121*
Stable
Whole blood72 h, EDTA13725% +/− 6% decrease in 24 hours
4°CWhole blood24 h, heparin134
4 days, heparin127
6 days, EDTA124*
8 days, unspecified anticoagulant136
Stable
−20°C to −30°CRBC lysate7 days116
21 days115
3 month108
Several month124
Stable
RBC lysate3 month1287% decrease
−70°C to −80°CRBC lysateFew days129,131
25 days116
Stable
RBC lysate16 month12815% decrease

Notes:

*

Control blood was stable for 7 days. Leukemia patient blood was stable for 3 days, and the median activity showed a small but statistically significant decrease after 6 days.

Abbreviations: EDTA = ethylene diamine tetra-acetic acid; RBC = red blood cell; TPMT = thiopurine methyltransferase.

Control blood was stable for 7 days. Leukemia patient blood was stable for 3 days, and the median activity showed a small but statistically significant decrease after 6 days.

From: 3, Results

Cover of Assessment of Thiopurine Methyltransferase Activity in Patients Prescribed Azathioprine or Other Thiopurine-Based Drugs
Assessment of Thiopurine Methyltransferase Activity in Patients Prescribed Azathioprine or Other Thiopurine-Based Drugs.
Evidence Reports/Technology Assessments, No. 196.
Booth RA, Ansari MT, Tricco AC, et al.

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