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Geisinger Medical Laboratories Test Catalog
THIOPURINE METABOLITES |
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ORDERING INFORMATION: |
Geisinger Epic Procedure Code: LAB3150 Geisinger Epic ID: 44147 | |
SPECIMEN COLLECTION |
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Specimen type: |
Whole blood | |
Preferred collection container: |
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Alternate Collection Container: |
6 mL lavender-top K2 EDTA tube
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Specimen required: |
5 mL whole blood; minimum 2.5 mL | |
Special notes: |
A trough specimen is required (within 1 hour prior to the next dose). | |
| SPECIMEN PROCESSING |
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Transport temperature: |
Refrigerated | |
Specimen stability: |
5 days | |
Rejection criteria: |
Hemolysis, heparinized whole blood; frozen specimen | |
TEST DETAILS |
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CPT code(s): |
80299 | |
| Note: The billing party has sole responsibility for CPT coding. Any questions regarding coding should be directed to the payer being billed. The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only. | ||
Test includes: |
6-Thioguanine (6-TG), 6-Methylmercaptopurine (6-MMP) | |
Methodology: |
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) |
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Synonyms: |
6-Methylmercaptopurine (6-MMP),6-MP,6-Thioguanine (6-TG),AZA, 6MP Quest test code 91745 THIPUR
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Clinical significance: |
6-Mercaptopurine (Purinethol) and its imidazolyl derivative, Azathioprine (Imuran), are immunosuppressive drugs. 6-Mercaptopurine (6-MP) is indicated for remission induction and maintenance therapy of acute lymphoblastic leukemia (ALL). Azathioprine is indicated as an adjunct for the prevention of rejection in renal allograft (kidney transplant) patients, for the management of rheumatoid arthritis, and for the management of inflammatory bowel disease. Azathioprine is cleaved to 6-MP. 6-MP is metabolized via a series of enzymatic steps to 6-thioguanine nucleotides (6-TGNs), to 6-methyl-mercaptopurine (6-MMPNs) by the enzyme thiopurine methyltransferase (TPMT), and to 6-thiouric acid by the enzyme xanthine oxidase (XO). TPMT enzyme activity has large inter-individual variations which affect the efficacy, toxicity and variability of the treatment. Therapeutic drug monitoring of 6-MP metabolites (6-TGNs and 6-MMPNs) in erythrocytes is recommended to assist therapy, particularly in combination with TPMT enzyme activity or mutation analysis. | |