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Test Code:
090-81-2010

Order Name:
Thiopurine Metabolites, Whole Blood **

 
Useful For:

Aids physicians in dose adjustments, minimizing dose-dependent toxicity, and monitoring compliance of thiopurine drug therapy

 
Methodology:
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
 
AliasesName:
6-Thioguanine Nucleotides (6-TGN) and 6-Methylmercaptopurine (6-MMP)
 
 
 
Test Code:
090-81-2010

Order Name:
Thiopurine Metabolites, Whole Blood **

 
Patient Preparation:
N/A
 
Collection Specimen Or Container:
Blood/ K3 EDTA (Lavender Top) 3 mL, 2 tubes

เจาะได้เฉพาะวันจันทร์-พุธก่อนเที่ยง (เว้นวันหยุดราชการ) Short Stability, sending to USA 
Collection Instructions: Send specimen in original tube. Do not aliquot, centrifuge, or freeze.
 
Specimen Testing Type:
EDTA whole blood, minimum volume 2 mL x 2 tubes
 
 
Sub Mission Container:
Original tube
 
Rejection Criteria:
Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Clotted Reject
 
Specimen Stabillity:
Specimen Type Temperature Time
Whole blood Refrigerated, 2oC to 8oC (preferred) 8 days
Ambient 24 hrs
**Sent out to MAYO, USA
 
 
 
 
Test Code:
090-81-2010

Order Name:
Thiopurine Metabolites, Whole Blood **

 
Method detail:
Red blood cell (RBC) count is first performed and then the thiopurine metabolites values are determined by mass spectrometry.(Unpublished Mayo Method)
 
Schedule:
N/A **Sent out to MAYO, USA
 
Turnaround Time:
Received specimen to report within 14 days
 
Performing Location:
MAYO Laboratory
Referral Lab Services, Laboratory Department 14160-2
 
 
 
Test Code:
090-81-2010

Order Name:
Thiopurine Metabolites, Whole Blood **

 
 
Clinical Information:
This test is primarily used to verify compliance, optimize therapy, and identify elevated metabolite concentrations that may result in toxicity after initiation of thiopurine drug therapy for the treatment of inflammatory bowel disease. Recommended time points for monitoring include: 4 weeks after starting treatment to verify patient compliance and look for early risk of toxicity; 12 to 16 weeks after starting therapy when 6-thioguanine nucleotides have reached steady-state; and annually.(1) It may also be ordered in patients who do not respond to therapy as expected or as needed for dose changes, flare-ups, signs of toxicity, or suspicion of noncompliance. The test will measure 6-methylmercaptopurine (6-MMP) and 6-thioguanine nucleotides (6-TGN) in erythrocytes.
 
Reference Value:

6-Thioguanine Nucleotides (6-TGN): 235-450 pmol/8x10(8) RBC
6-Methylmercaptopurine (6-MMP): Less than or equal to 5700 pmol/8x10(8) RBC

 
Interpretation:
Target 6-thioguanine (6-TGN) concentrations are 235 to 450 pmol/8x10(8) RBC with lower levels suggesting suboptimal dosing and higher levels associated with increased risk of myelotoxicity and leukopenia. High 6-methylmercaptopurine (6-MMP) levels (greater than 5700 pmol/8x10[8] RBC) suggest an increased risk for hepatotoxicity and potentially "thiopurine hypermethylation."

Cautions: This test cannot be used to predict optimal starting dose. It is sensitive to hemolysis and transport conditions. This test does not replace monitoring of patients using other laboratory tests (ie, CBC, liver function tests).
 
Clinical Reference:
www.mayomedicallaboratories.com (Retrieved: 02 Sep 2020)