I was on 1.25mcg Synthroid until about a month ago when my dose was increased to 1.50mcg. I am 42 years old and wondering if my body is no longer converting T4 to T3 as well as it did before. I am also wondering if Armour would be a better choice for me. If so how would I transition the two medications. I've really been feeling the symptoms associated with hypothyroidism. Does anyone know the long term effects of being on Synthroid?