I've just been to see a private endo in Edinburgh and he has informed me that not only were my beta blockers (for migraine) stopping the thyroxine from working properly, but also tablets precribed for vertigo/Meuniere's Disease (Beta histene) had some side effects that mimicked hypothyroidism symptoms. He also told me that he would write to my GP informing him of his findings and to 'go' with the symptoms rather than than the 'range of results'. Allelujah - at last someone talking sense. As a result, although my results are 'within range' because I'm symptomatic he has upped my thyroxine from 100 to 125 and says it may have to go up as the thyroid output reduces with age. Hope this helps some of you that are struggling with treatment.