Expected Turnaround Time
7 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Whole blood
Volume
3 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Lavender-top (EDTA) tube or yellow-top (ACD) tube
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 28 days |
Refrigerated | 28 days |
Causes for Rejection
Frozen sample; hemolysis
Test Details
Use
Detects the most common genotypes in approximately 95% of patients. Use is recommended prior to initiating thiopurine therapy.1
Limitations
This assay will not detect approximately 5% of known deficiency mutations, and only the exons containing mutations in question are tested; polymorphisms or some sequence variants might affect efficiency of the PCR or mini-sequencing assays; assay does not distinguish between TPMT*1/3A heterozygote and the very rare compound heterozygote TPMT*3B/3C.
This test was developed, and its performance characteristics determined, by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Polymerase chain reaction (PCR) and multiplex mini-sequencing
Footnotes
References
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 508080 | TPMT Genetic Test | 41048-0 | 508081 | TPMT Genotype | 41048-0 | |
| 508080 | TPMT Genetic Test | 41048-0 | 508082 | TPMT Interpretation | 62365-2 | |
| 508080 | TPMT Genetic Test | 41048-0 | 508083 | TPMT Comment | 77202-0 | |
| 508080 | TPMT Genetic Test | 41048-0 | 508084 | TPMT Genetic Test | N/A |
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