Hyperthyroidism refers to a pathophysiological condition in which the thyroid gland produces and releases abnormally high levels of the thyroid hormones (T₃ and T₄).

The symptoms of hyperthyroidism may include high metabolic rate, weight loss, nervousness, excess heat production, tachycardia, and tremor.

Two main forms of hyperthyroidism exist: (1) Primary hyperthyroidism, and (2) Secondary hyperthyroidism.

In primary hyperthyroidism, the thyroid gland produces high levels of the thyroid hormones, either as a result of a secretory tumor of the thyroid gland, or under the control of thyroid stimulating immunoglobulins (such as in Graves' disease).

Secondary hypothyroidism is caused by high levels of thyroid stimulating hormone (TSH) produced by the anterior pituitary gland. TSH then stimulates the thyroid gland to produce excessive amounts of the thyroid hormones.

Hypothyroidism
Euthyroidism

Protrusion or bulging of one or both eyeballs out of the orbit. It may be caused by swelling of orbital tissue in response to trauma, or by hyperthyroidism (especially primary hyperthyroidism).

It is also referred to as exophthalmus, exophthalmia, proptosis, or exorbitism.

Exophthalmos (Wikipedia)