TPMT (Thiopurine methyltransferase) Activity
Order Name
TPMT ACT
Test Number: 3601957
Revision Date 03/05/2024
Test Number: 3601957
Revision Date 03/05/2024
| Test Name | Methodology | LOINC Code |
|---|---|---|
|
TPMT (Thiopurine methyltransferase) Activity
|
Enzymatic/Quantitative Liquid Chromatography-Tandem Mass Spectrometry | 53819-9 |
| SPECIMEN REQUIREMENTS | ||||
|---|---|---|---|---|
| Specimen | Specimen Volume (min) | Specimen Type | Specimen Container | Transport Environment |
| Preferred | 8 mL adult; 5 mL pediatric (5 mL) | Whole Blood | Sodium Heparin (Green Top / No-Gel) | Refrigerated |
| Alternate 1 | 8 mL adult; 5 mL pediatric (5 mL) | Whole Blood | EDTA (Lavender Top) | Refrigerated |
| Instructions | Specimen Type: Green-top (sodium heparin) tube or lavender-top (EDTA) tube Specimen Storage: Refrigerate Specimen Collection: Not Available Special Instructions: For New York state patients: Test orders for TPMT Enzyme Act Activity MUST include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form (Informed Consent for TPMT Enzyme Activity Specimen Stability: Ambient: Not Available, Refrigerated : 14 days, Frozen: Unstable |
|||
| GENERAL INFORMATION | |
|---|---|
| Expected TAT | 7-12 days |
| Clinical Use | Help prevent hepatotoxicity from thiopurine therapy. This test helps identify individuals at increased risk of hepatotoxicity from thiopurine dose escalation. Patients with a TMPT activity of 4-12 nmol 6-MMP/hr/mL RBC (heterozygote/low metabolizer) are at increased risk and may require a lower dose of thiopurine drug. |
| CPT Code(s) | 84433 |
| Internal Comments | This test was added 06/16/2014, but NRHS requested this be added to their catalog 8/7/17 - JK 8/28/17 moved to arup - JK 2/1/18 Change in CPT 83789 from to 82657 3/5/24 Change in CPT to 84433 from 82657 hdm |
| Lab Section | Reference Lab |