TPMT and hyperinsulinemic hypoglycemia, familial, 4: The cost-effectiveness model for azathioprine, based on parameters collected for TPMT genotyping costs, estimates for frequency of TMPT deficiency, rates of thiopurine-mediated myelosuppression in TPMT-deficient individuals, and myelosuppression-related hospitalization costs, established that TPMT testing in all patients had a favorable cost-effectiveness ratio (107).