I also was diagnosed with hyperthyroidism in Sept 2011. I became very sick quick, losing alot of fluids, no appetite, & very weak. I lost 55 lbs within a month. I was given the radioactive pill on 10/20/11. I gradually started to feel better, got my appetite back, & gained back 25 lbs. In January of this year, my hormones swung opposite, & I am now hypo. They started me on a low dose of levothyroxine & are slowly increasing the dosage to get me leveled out. I too have been very irritable, have hair loss, & get very frustrated because I can't remember common everyday words. My hair is also like it has been burnt; very dry & breaks off easy. I'm wondering if I will ever be back to my normal self, although the discussions here have been somewhat encouraging.