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Thiopurine Metabolites : 91745
Test CodeTHIPU or 91745
Alias/See Also
6-Methylmercaptopurine (6-MMP),6-MP,6-Thioguanine (6-TG),AZA
CPT Codes
80299
Instructions
A trough specimen is required (within 1 hour prior to next dose).
Transport Container
Preferred Specimen
5 mL whole blood collected in an EDTA (lavender-top) tube
Minimum Volume
2.5 mL
5 mL whole blood collected in an EDTA (lavender-top) tube
Minimum Volume
2.5 mL
Transport Temperature
Refrigerated.
Specimen Stability
Room temperature: 24 hours; Refrigerated: 7 days: Frozen: Unacceptable
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis, Heparin whole blood, received frozen
Methodology
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Setup Schedule
Tuesday - Saturday
Report Available
2- 4 days
Reference Range
6-TG 235-400 pmol/8x10(8)RBC
6-MMP <5700 pmol/8x10(8)RBC
6-MMP <5700 pmol/8x10(8)RBC
Clinical Significance
Thiopurine Metabolites - 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.
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.
Performing Laboratory
med fusion