Imatinib therapy in chronic myelogenous leukemia and thyroid function tests

Imatinib, a tyrosine kinase inhibitor which resulted in much improvement in the treatment of chronic myelogenous leukemia (CML), may adversely affect thyroid gland function. To date, assessment of thyroid function during imatinib therapy has limited to retrospective studies. The aim of this study was to evaluate the effects of imatinib on thyroid function in a prospective manner.

In this prospective study, 16 newly diagnosed adult subjects with positive Philadelphia chromosome in chronic phase of CML without any other apparent underlying diseases were enrolled. Free T3, Free T4, TSH, Anti TPO and Anti thyroglobulin antibodies were measured before and after 4 and 12 weeks of treatment.

Of the 16 patients, 9 were male (57.1%) and 7(42.9%) were female with a mean age of 29±5 years. There were statistically significant changes within reference ranges in serum concentrations of TSH (P=0.753 and 0.002), Free T3 (P=0.012 and 0.007) and Anti Thyroglobulin (P=0.221 and 0.041) 1 month before and 3 months after imatinib initiation, respectively. At the same time, there were no significant changes in serum Free T4 (P=0.196 and 0.650) and Anti TPO (P=0.807 and 0.600) concentrations.

This study showed some significant changes on thyroid function tests during imatinib therapy. However, all of them were within the normal range without any clinical abnormalities in the course of treatment. We recommend other studies with larger sample size and longer duration of follow-up.