Decreased to no NUDT15 enzyme activity. Increased to greatly increased risk of thiopurine-related leukopenia, neutropenia, myelosuppression based on NUDT15 alone.
Important Instructions: Please use TPMT phenotype to select the appropriate recommendation below.
TPMT Normal Metabolizer
Normal TPMT enzyme activity. Normal risk of thiopurine-related leukopenia, neutropenia, myelosuppression based on TPMT alone.
Therapeutic Recommendation
- For malignant conditions: Start with drastically reduced doses (reduce daily dose by 10-fold). Allow 4–6 weeks to reach steady-state after each dose adjustment.
- For nonmalignant conditions: Consider alternative nonthiopurine immunosuppressant therapy.
TPMT Intermediate Metabolizer
Decreased TPMT enzyme activity. Increased risk of thiopurine-related leukopenia, neutropenia, myelosuppression based on TPMT alone.
Therapeutic Recommendation
- For malignant conditions: Start with drastically reduced doses (reduce daily dose by 10-fold). Allow 4–6 weeks to reach steady-state after each dose adjustment.
- For nonmalignant conditions: Consider alternative nonthiopurine immunosuppressant therapy.
TPMT Poor – Intermediate Metabolizer
Decreased to no TPMT enzyme activity. Increased to greatly increased risk of thiopurine-related leukopenia, neutropenia, myelosuppression based on TPMT alone.
Therapeutic Recommendation
- For malignant conditions: Start with drastically reduced doses (reduce daily dose by 10-fold and dose thrice weekly instead of daily). Allow 4–6 weeks to reach steady-state after each dose adjustment.
- For nonmalignant conditions: Consider alternative nonthiopurine immunosuppressant therapy.
TPMT Poor Metabolizer
No TPMT enzyme activity. Greatly increased risk of thiopurine-related leukopenia, neutropenia, myelosuppression based on TPMT alone.
Therapeutic Recommendation
- For malignant conditions: Start with drastically reduced doses (reduce daily dose by 10-fold and dose thrice weekly instead of daily). Allow 4–6 weeks to reach steady-state after each dose adjustment.
- For nonmalignant conditions: Consider alternative nonthiopurine immunosuppressant therapy.