Preanalytical stringency: what factors may confound interpretation of thiopurine S-methyl transferase enzyme activity?
Author(s): van Egmond R, Barclay ML, Chin PK, Sies CW, Florkowski CM
Publication: Ann Clin Biochem, 2013, Vol. 50, Page 479-84
PubMed ID: 23812896 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine the effects of patient age and gender, geographical location within New Zealand, storage duration, and blood transport duration on levels of thiopurine S-methyl transferase (TPMT) in blood cell lysates.
Conclusion of Paper
TPMT activity in blood cell lysates decreased with longer storage duration or blood transport time and increased with patient age. TPMT activity in blood cell lysates was higher in men than women and after correcting for transport in specimens from Auckland, NZ than specimens from Christchurch, NZ.
Studies
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Study Purpose
The purpose of this study was to determine the effects of patient age and gender, geographical location within New Zealand, storage duration, and blood transport duration on levels of TPMT in blood cell lysates. EDTA blood was stored at 4-6 degrees C for 0 or 72 h before transport on ice and storage in the laboratory for up to 3 days at 4-6 degrees C. Blood was then centrifuged to obtain blood cells. The blood cells were lysed in cold water and stored frozen at -20 degrees C for up to one week before analysis.
Summary of Findings:
TPMT activity in blood cell lysates was negatively associated with increased blood storage (p<0.0001). On average, TPMT activity in blood cell lysates decreased by 0.016 IU/mL per hour of storage of blood. Delayed processing due to transportation of the blood significantly decreased TPMT activity by 0.011 IU/mL/hour in blood cell lysates (p<0.001). TPMT activity in blood cell lysates increased by 0.008 IU/mL per each additional year of patient age (p<0.001). TPMT activity in blood cell lysates was 4% higher in men than women (p<0.001). The geographical location at which sampling was performed also significantly affected TPMT activity with specimens from Auckland, NZ having higher transport corrected levels than specimens from Christchurch, NZ (p<0.001), but all other regions had comparable levels to Christchurch.
Biospecimens
Preservative Types
- Other Preservative
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Protein Radioassay Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage duration 0 h
72 h
Preaquisition Patient age 0-94 years
Preaquisition Patient gender Female
Male
Storage Between site transportation method Air courier
Storage Specimen transport duration/condition 1 h
51.47 h
48.95 h
25.30 h
42.97 h
24.5 h
24.0 h