 Females are four times more likely to develop TAO than males.When males are affected, they tend to have a later onset and a poor prognosis.A study demonstrated that at the time of diagnosis, 90% of the patients with clinical orbitopathy were hyperthyroid according to thyroid function tests, while 3% had Hashimoto's thyroiditis, 1% were hypothyroid and 6% did not have any thyroid function tests abnormality.