Changes in serum diamine oxidase activity during chemotherapy in patients with hematological malignancies

Serum diamine oxidase (DAO) activity is very low, but is considered to reflect quantitative changes in small intestinal mass. Therefore, we measured DAO activity during chemotherapy in patients with hematological malignancies in order to evaluate mucosal injury. DAO activity decreased from 1-3 weeks after chemotherapy but returned to initial levels after 4 weeks. As the dosage of anti-cancer drugs increased, DAO activity decreased more, but its activity was not related to other parameters. These findings suggest that serum DAO could be used as an indicator of mucosal injury during chemotherapy.