Thiopurine Methyltransferase (TPMT), Enzyme Activity, Erythrocytes
Also known as: TPMT Biochemical Assay, Myelotoxicity
Use
Determination of TPMT levels that may be associated with toxicity of anticancer and anti-inflammatory drugs
Special Instructions
Patients with an intrinsic low level of TPMT may have increased enzymatic activity due to recent RBC transfusion. It is critical to consider this potential variability when interpreting results, as transfused red blood cells can influence the assay's enzymatic activity readings.
Limitations
The test was developed and its performance characteristics determined by Labcorp, but it has not been cleared or approved by the Food and Drug Administration. Additionally, recent RBC transfusions might obscure the intrinsic TPMT level, potentially skewing results by artificially elevating enzymatic activity depending on the proportion and lifespan of transfused cells.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 79713-4
- 21563-2
- 79713-4
- 49549-9
Result Turnaround Time
7-12 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
8 mL adults; 5 mL pediatric
Minimum Volume
5 mL
Container
Green-top (sodium heparin) tube or lavender-top (EDTA) tube
Storage Instructions
Refrigerate
Causes for Rejection
Frozen specimen; gross hemolysis; clotted specimen
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 14 days |
| Frozen | Unstable |