Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 21 9 2018 09 01 Tryptophan Degradation and Antioxidant Status in Patients With Thyroid Disorders 399 405 EN Songül Ünüvar Gözde Girgin Tevfik Tolga Şahin Bilge Kılıçarslan Ferit Taneri Osman Yüksel Terken Baydar Journal Article 2018 01 18 2018 07 02 Background: The aim of this study was to evaluate the degradation of tryptophan (Trp), neopterin production and antioxidant capacity in patients with benign and malignant thyroid disease. Methods: For this reason, the levels of tryptophan, kynurenine (Kyn) and neopterin, and superoxide dismutase (SOD) and catalase (CAT) enzyme activities in 67 thyroid patients were evaluated in our study and the results were compared with 30 healthy controls. Results: Tryptophan and kynurenine levels in thyroid patients decreased compared to the control group. Patients with thyroid disease had lower CAT activity than the control group. The neopterin and tryptophan levels in malignant and benign patients were also significantly different. Conclusion: The results of the present study suggest that thyroid disorders may lead to changes in tryptophan degradation, neopterin production and CAT enzyme activities