Frequent lurker, occasional poster here--I'm hoping someone might have input on TKI-related endocrine issues.
I was diagnosed in January 2011 and was on 400 mg Gleevec until February 2012 when I switched to Sprycel, both because my response had plateaued on Gleevec and also because I was experiencing symptoms that my oncologist and I thought might be Gleevec side effects--severe lightheadedness, bad muscle pain and weakness, loss of appetite, nausea, headaches, and joint pain. My symptoms were (and are) worst when I am up and around and improve when I lie down. I switched in late February and these symptoms did not improve. Because my chief complaint was lightheadedness, my onc referred me to a neurologist, who did a thorough neuro exam and sent me for an MRI of my brain. All of that was normal. The neurologist suggested that I get some endocrine labs run, specifically free cortisol. (Persistent lightheadedness and some of my other symptoms can be symptoms of adrenal dysfunction.) She did not feel confident interpreting them so she referred me to an endocrinologist. I was not able to get into any of the endos she recommended before May, so in what turned out to be a lucky break, I ended up seeing an endo recommended by a friend.
He did his fellowship at Sloan Kettering and had a lot of experience with patients who were on sunitinib, another TKI used for renal cell carcinoma. He told me that thyroid problems, in particular, were extremely common among those patients. He knew about the paper on Gleevec patients who had had their thyroids removed and needed more thyroid replacement hormone after starting on Gleevec. He explained that the best guess about the mechanism at work there is some form of peripheral thyroid hormone resistance--the Gleevec prevents thyroid hormone from binding in some way so even with normal amounts of hormone it is not able to do its work in the body. This means that patients have normal thyroid labs but are nonetheless hypothyroid. Taking all of this into account, the endo said that even if my thyroid labs come back normal, given my symptoms he is willing to have me try some thyroid hormone and see if my symptoms improve.
I'm interested in hearing whether anyone here has had an endocrine workup post-dx (and what it showed) and whether anyone has tried thyroid (and/or adrenal) hormone supplementation despite normal lab values. I'm wondering whether anyone has gotten relief from these kinds of symptoms in this way. I'm also curious whether anyone had significant changes in hormone levels pre- and post-TKI. I get my labs back this week so any info would be helpful for follow-up discussions.