I am 43 years old and hypothyroid for 4 years. I have been on synthroid that time. When I first went on it i felt great, lost weight and was doing well. Im tired, brain fog, gaining weight (quickly) joint pain and a few other hypo symptoms again. I am normally a very active person. My blood test show my levels are within normal range but, i sure don t feel like it. And my liver enzymes came back elevated.