Based on TPMT status, for non-malignant conditions, consider alternative non-thiopurine immunosuppressant therapy. For malignancy, start with drastically reduced doses (reduce daily dose by 10-fold and dose thrice weekly instead of daily) and adjust doses of azathioprine based on degree of myelosuppression and disease-specific guidelines. Allow 4-6 weeks to reach steady-state after each dose adjustment (PMID 16530578, 11302950, 15606506, 16530532, 12477776). NUDT15 status could not be determined based on genotyping. If thiopurines are required and NUDT15 status is unknown, monitor closely for toxicity.