Table 5.
Interpretation of Thiopurine Metabolites
| 6-TGN level (pmol/8 × 108 RBCs) | 6-MMPR level (pmol/8 × 108 RBCs) | Interpretation | Change in therapy |
|---|---|---|---|
| 235–450 | < 5,700 | Normal levels | None |
| Undetectable | Undetectable | Non adherence | Counselling |
| < 235 | < 5,700 | Subtherapeutic | Increase the dose |
| > 450 | Low, normal or high | Supratherapeutic | Reduce the dose |
| < 235 | > 5,700 | Shunter to 6-MMPR with risk of hepatotoxicity | Reduce AZA and add allopurinol |
6-TGN, 6-thioguanine nucleotides; 6-MMPR, 6-methyl mercaptopurine ribonucleotides; RBCs, red blood cells; AZA, azathioprine.