Test Catalog

Test ID: FPMET    
Prometheus Thiopurine Metabolites

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Units of Measure:  pmol/8 x 10(8) RBC


Metabolite                                                   Reference Range

6-TGN                                                                 230-400

6-MMPN                                                              <5700


Proprietary and patented technology by Prometheus Laboratories, Inc.  The therapeutic range and toxic thresholds were established in an IBD patient population receiving azathioprine or 6-mercaptopurine.  Metabolite testing should not replace laboratory monitoring for toxicity.


Clinical Reference Recommendations for in-depth reading of a clinical nature

Dubinsky M, et al. Pharmacogenomics and metabolite

measurement for 6-mercaptopurine therapy in patients with

inflammatory bowel disease.  Gastroenterology.  2000;118:705-713.


Seidman EG. Recent Advances in the diagnosis and treatment

of pediatric inflammatory bowel disease.  Gastroenterol Rep.2000;



Cuffari C, et al. Utilisation of erythrocyte 6-thioguanine metabolite

levels to optimize azathioprine therapy in patients with inflammatory

bowel disease. Gut. 2001;48:642-646.


Seidman, EG. Clinical use and practical application of TPMT Enzyme

and 6-mercaptopurine metabolite monitoring in IBD. Rev

Gastroenterol Disord. 2003;3(suppl 1):S30-S38.


Rumbo C, et al. Azathioprine metabolite measurements in the

treatment of autoimmune hepatitis in pediatric patients: A preliminary

report. J Ped Gastro Nutr. 2002;35:391-398.


Lennard L, et al. The clinical pharmacology of 6-mercaptopurine.

Eur J Clin Pharmacol. 1992;43(4):329-339.


Lennard L. Clinical implication of thiopurine methyltransferase-Optimization

of drug dosage and potential drug interactions. Ther Drug Monit 1998;



Louis E, Belaiche J. Optimizing treatment with thioguanine derivative

in inflammatory bowel disease.  Best Pract Res Clin Gastroenterol