Thiopurine Metabolites in Red Blood Cells
Use this phenotyping test to optimize dosing of thiopurine drugs. This test can identify thiopurine metabolite (6-TGN and 6-MMPN) concentrations that may contribute to risk of toxicity.
For enzyme phenotyping prior to thiopurine treatment, refer to Thiopurine Methyltransferase, RBC (0092066). For pharmacogenetic testing (prior to or during treatment), refer to TPMT and NUDT15 (3001535).
Quantitative Liquid Chromatography-Tandem Mass Spectrometry
Tue, Thu, Sat
New York DOH Approval Status
Trough collection (within 1 hour prior to the next dose).
Lavender (EDTA) or pink (K2EDTA).
Transport 5 mL whole blood. (Min: 2.5 mL)
Gel separator tubes. Hemolyzed or lipemic specimens. Frozen specimens.
Ambient: 24 hours; Refrigerated: 7 days; Frozen: Unacceptable
Thiopurine drug therapy is used to treat autoimmune diseases, inflammatory bowel disease, acute lymphoblastic leukemia, and to prevent rejection after solid organ transplant. Thiopurine drugs are metabolized to active 6-thioguanine nucleotides, which are regulated by thiopurine methyltransferase (TPMT) and nudix hydrolase 15 (NUDT15). Certain variants in the TPMT and/or NUDT15 genes can be associated with an accumulation of cytotoxic metabolites that increase the risk of drug-related toxicity with standard doses of thiopurine drugs. Thiopurine metabolites concentrations are used to assess therapeutic and toxic concentrations of thiopurine drugs.
|INTERPRETIVE INFORMATION: Thiopurine metabolites
|Therapeutic range (optimal dosing)||235-450 pmol 6-TGN/8x10^8 red blood cells|
|Suboptimal dosing||<235 pmol 6-TGN/8x10^8 red blood cells|
|Increased risk for toxicity||>450 pmol 6-TGN/8x10^8 red blood cells may increase the risk for myelotoxicity and leukopenia|
|Increased risk for toxicity||>5700 pmol 6-MMPN/8x10^8 red blood cells may increase the risk for hepatotoxicity|
Laboratory Developed Test (LDT)
80299 (Alt code: G0480)
|Component Test Code*||Component Chart Name||LOINC|
- 6 Methyl Mercaptopurine
- Imuran Metabolite
- Purine antimetabolites
- Thiopurine Metabolites