{"Thioguanine can be affected by a patient's TPMT and NUDT15 phenotype. This patient is predicted to be a NUDT15 intermediate metabolizer and is at risk for myelosuppression with normal doses of thioguanine. Start with reduced doses (50% to 80% of normal dose) if normal starting dose is ≥ 40-60 mg/m2/day (e.g., 20-48 mg/m2/day) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, and depending on other therapy, emphasis should be on reducing thioguanine over other agents. However, TPMT phenotype could not be assigned based on genotyping performed. Consider evaluating TPMT erythrocyte activity to assess TPMT phenotype. Erythrocyte TPMT activity test results can be falsely low at diagnosis of leukemia and is unreliable in the case of recent red blood cell transfusions. If thiopurines are required and TPMT status is unknown, monitor closely for toxicity. Please consult a clinical pharmacist for more information."}