They said it was free T3 of 5.3 and the range is 3.1 - 6.8. This seems normal so I've no idea why I have so many symptoms of an under active thyroid, especially when my T4 is usually high. Though in the last test it was normal. I'm worried it may be something to do with my pituitary or is my thyroid just 'burning itself out'. My antibody test showed I have thyroid stimulating antibodies which I guess means Graves' disease which my mum had but hers soon turned underactive. The weight gain, my slow reflex response and the fact that I'm always freezing and have chronic constipation just doesn't add up. Could anyone help with this?