This, in turn, causes the clinical symptoms of hyperthyroidism, and the enlargement of the thyroid gland visible as goiter. The infiltrative exophthalmos frequently encountered has been explained by postulating that the thyroid gland and the extraocular muscles share a common antigen which is recognized by the antibodies. Antibodies binding to the extraocular muscles would cause swelling behind the eyeball. The "orange peel" skin has been explained by the infiltration of antibodies under the skin, causing an inflammatory reaction and subsequent fibrous plaques. The three types of autoantibodies to the TSH receptor currently recognized are:

Thyroid stimulating immunoglobulins: these antibodies (mainly IgG) act as long-acting thyroid stimulants, activating the cells through a slower and more drawn out process compared to TSH, leading to an elevated production of thyroid hormone. Thyroid growth immunoglobulins: these antibodies bind directly to the TSH receptor and have been implicated in the growth of thyroid follicles. Thyrotrophin binding-inhibiting immunoglobulins: these antibodies inhibit the normal union of TSH with its receptor. Some actually act as if TSH itself is binding to its receptor, thus inducing thyroid function. Other types may not stimulate the thyroid gland, but prevent TSI and TSH from binding to and stimulating the receptor.Another effect of hyperthyroidism is bone loss from osteoporosis, caused by an increased excretion of calcium and phosphorus in the urine and stool. The effects can be minimized if the hyperthyroidism is treated early. Thyrotoxicosis can also augment calcium levels in the blood by as much as 25%. This can cause stomach upset, excessive urination, and impaired kidney function.
Serologically detected thyroid-stimulating antibodies, radioactive iodine (RAI) uptake, or thyroid ultrasound with Doppler all can independently confirm a diagnosis of Graves disease. Biopsy to obtain histiological testing is not normally required, but may be obtained if thyroidectomy is performed. The goiter in Graves disease is often not nodular, but thyroid nodules are also common. Differentiating common forms of hyperthyroidism such as Graves disease, single thyroid adenoma, and toxic multinodular goiter is important to determine proper treatment. The differentiation among these entities has advanced, as imaging and biochemical tests have improved. Measuring TSH-receptor antibodies with the h-TBII assay has been proven efficient and was the most practical approach found in one study. Eye disease
Thyroid-associated ophthalmopathy (TAO), or thyroid eye disease (TED), is the most common extrathyroidal manifestation of Graves disease. It is a form of idiopathic lymphocytic orbital inflammation, and although its pathogenesis is not completely understood, autoimmune activation of orbital fibroblasts, which in TAO express the TSH receptor, is thought to play a central role.Hypertrophy of the extraocular muscles, adipogenesis, and deposition of nonsulfated glycosaminoglycans and hyaluronate, causes expansion of the orbital fat and muscle compartments, which within the confines of the bony orbit may lead to dysthyroid optic neuropathy, increased intraocular pressures, proptosis, venous congestion leading to chemosis and periorbital edema, and progressive remodeling of the orbital walls.