Thiopurine Metabolites : 91745

Test Code
THIPU 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


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


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.


Performing Laboratory
med fusion



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.