Background: Thyroid dysfunction is a known adverse effect of some tyrosine kinase inhibitors like sunitiniband sorafenib while imatinib hasbeen shown to induce hypothyroidism and increased requirement of levothyroxine in thyrectomizedpatients. Very few retrospective studies are available for CML patients treated with imatinib,which havedemonstrated conflicting effects on thyroid function.Experimental design: We have prospectively studied thyroid function at baseline and at 6 months of imatinib treatment in 30 newly diagnosed BCR-ABL positive CML patients.Results: Two (6.7%) patients had subclinical hypothyroidism at diagnosis with the prevalence not being different from general population. Though the TSH levels increased significantly from baseline (3.80±2.00 mIU/L vs. 3.14±1.65 mIU/L, p =0.016) after6 months of treatment, 90% of the patients remained euthyroid. Only 3 patients had subclinical hypothyroidism.Conclusion: Imatinib did not have any significant impact on thyroid function in CML patients but may possibly alter the peripheral metabolism of thyroid hormones
