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Test Code THIOP Thiopurine Metabolites, Whole Blood

Reporting Name

Thiopurine Metabolites, B

Useful For

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

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole Blood EDTA

Shipping Instructions

Specimen must be shipped refrigerated.

Specimen Required

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot, centrifuge, or freeze.

Specimen Minimum Volume

1.5 mL

Testing Algorithm

A red blood cell (RBC) count is performed followed by determined of thiopurine metabolite values by liquid chromatography-tandem mass spectrometry. Values are utilized to calculate and report a final result (unit of measure: pmol/8 x 10[8] RBC) for 6-thioguanine nucleotides and 6-methylmercaptopurine derivative analyte.

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated (preferred) 8 days
  Ambient  24 hours

Reference Values

6-Thioguanine Nucleotides (6-TGN): 235-450 pmol/8x10(8) red blood cell (RBC)

6-Methylmercaptopurine (6-MMP): Less than or equal to 5700 pmol/8x10(8) RBC

Day(s) Performed

Monday through Friday

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
THIO Thiopurine Metabolites, B 82869-9


Result ID Test Result Name Result LOINC Value
49580 6-Thioguanine Nucleotides 32660-3
49581 6-Methylmercaptopurine 32654-6

Clinical Reference

1. Goel RM, Blaker P, Mentzer A, Fong SCM, Marinaki AM, Sanderson JD: Optimizing the use of thiopurines in inflammatory bowel disease. Ther Adv Chronic Dis. 2015 May;6(3):138-146

2. Shipkova M, Armstrong VM, Wieland E, Oellerich M: Differences in nucleotide hydrolysis contribute to the differences between erythrocyte 6-thioguanine nucleotide concentrations determined by two widely used methods. Clin Chem. 2003 Feb:49(2):260-268

3. Boulieu R, Dervieux T: High-performance liquid chromatographic determination of methyl 6-mercaptopurine nucleotides (Me6-MPN) in red blood cells: analysis of Me6-MPN per se or Me6-MPN derivative? J Chromatogr B Biomed Sci Appl. 1999 Jul 9;730(2):273-276

4. Kirchherr H, Shipkova M, von Ahsen N: Improved method for therapeutic drug monitoring of 6-thioguanine nucleotides and 6-methylmercaptopurine in whole-blood by LC/MSMS using isotope-labeled internal standards. Ther Drug Monit. 2013 Jun:35(3):313-321

Method Description

Red blood cell count is first performed and then the thiopurine metabolites values are determined by mass spectrometry.(Unpublished Mayo Method)

Report Available

2 to 4 days

Reject Due To

Gross hemolysis Reject
Moderate hemolysis Reject
Gross lipemia OK
Gross icterus OK
Clotted Reject

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)


If not ordering electronically, complete, print, and send Gastroenterology and Hepatology Client Test Request (T728) with the specimen

Secondary ID