en Adults Hematology & Oncology Adults Hematology & Oncology پژوهشي Original Article <p>Background: Imatinib mesylate is the first generation of Tyrosine kinase inhibitors (TKI) and highly effective in the treatment of chronic myeloid leukemia (CML). We aimed to evaluate thyroid function at baseline and at 1, 3, 6 and 12 months after initiation of Imatinib mesylate therapy in 20 newly diagnosed BCR-ABL positive CML patients.<br> Methods: This study was done during 2013-2014, 20 new cases with Philadelphia chromosome-positive CML without any underlying thyroid disorder or drug history interfering with Imatinib mesylate were enrolled. Thyroid function tests including serum Thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), anti-thyroid peroxidase (Anti-TPO) and anti-thyroglobulin (Anti-Tg) were assessed at baseline and during follow-up.<br> Results: Mean age at diagnosis was 60.4 years. 14 (70%) patients were male. &nbsp;Mean value for TSH, FT4, FT3, Anti-TPO, and Anti-Tg before treatment were 2.82 mIU/L, 1.39 ng/dl, 325.50 ng/dl, 30.35 IU/ml and 39.40 IU/ml, respectively. The mean value for TSH, FT4, FT3 and Anti-TPO 1, 3, 6, and 12 months after initiation of Imatinib mesylate were not statistically significant.<br> Conclusion: Based on the results of the study, there was no significant change in thyroid function tests during treatment with Imatinib mesylate and all laboratory variables were in normal ranges.&nbsp;</p> Chronic myeloid leukemia, Imatinib, Thyroid dysfunction, Thyroid function tests 9 12 http://ijbc.ir/browse.php?a_code=A-10-218-8&slc_lang=en&sid=1 Abolghasem Allahyari allahyari@yahoo.com 10031947532846003257 10031947532846003257 No Department of Hematology-Oncology, Emam Reza Hospital, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Foroogh Salehi f.salehi@yahoo.com 10031947532846003258 10031947532846003258 No Department of Endocrinology, Vali Asr Hospital, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran Mostafa Kaboli m.kaboli@gmail.com 10031947532846003259 10031947532846003259 No Department of Internal Medicine, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran Masoud Sadeghi sadeghi_mbrc@yahoo.com 10031947532846003260 10031947532846003260 Yes Cancer Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran