Grave's disease is an autoimmune disorder which affects the thyroid gland, causing it to enlarge and increase its activity, determining symptoms of hyperthyroidism. The  disease is determined by the body's production of antibodies to the receptors fos TSH, the tireostimulating hormone. These antibodies bind to the receptors and stimulate it. As a result the folicular thyroid cells multiply, resulting an increased production of thyroid hormones(T3 and T4) and to hyperthyroidism.  The triggering factors of this abnormal immune reactions are : infection (viral and bacterial)  and severe stress. There have been studies trying to prove the genetic inheritance of Grave's disease but until now it has not been identified a gene responsible of triggering this disorder.

The signs and symptoms of Grave's disease are determined not only by the disease itself but also by the consequent hyperthyroidism. The most common features of the disease are: exophtalmos, pretibial myxedema, increased heart rate, fatigue, muscular weakness and symptoms related to hyperthyroidism.

Graves' ophtalmopathy or thyroid associated ophtalmopathy is the most typical finding in the patients suffering from this disorder. It determines the inflammation of the eyes and the tissues around them, including the orbital fat and the exterior muscles of the eyes and determining a  bulging aspect  of the eyes and optic nerve compression. In the early stages of Grave's ophtalmopathy the patient complains of eyelid retraction, irritation, photophobia. tearing and lagophtalmos (the incapacity of closing the eyes completely). As the disease progresses the symptoms become more marked and the extraocular muscles are affected (myopathy).

Due to the damage and fibrosis of the inferior rectus muscle, the patient will develop vertical diplopia, increased intraocular pressure and intermittent double vision. In the late stages of Grave's ophtalmopathy, exophtalmos occurs (leading to an impaired eye movement and optic neuropathy and optic nerve compression). The patient's visual acuity decreases, visual field defect, loss of color vision and afferent pupilary deffect occur. In this stage, any delay in treatment may lead to permanent blindness.

The goitre and the Graves' ophtalmopaty are the only symptoms directly determined by the disease. The other symptoms, caused by the increased levels of thyroid hormones are: hypertension, tachycardia, palpitations, fatigue, irritability, decreased concentration and diminished attention span. Dyspnea (shortness of breath), muscular weakness (especially in the muscles of the limbs), insomnia, and dry, brittle hair and nails are also common.

The disease may also have dermatological manifestations consisting in hypersensitivity reactions, erythema anulare centrifugum (a type of rash in which the central area clears as the eruption spreads). Acropachy, a condition similar to elephantiasis occurs rarely.

The hyperthyroidism has a marked impact on the patient's metabolism, leading to hyperglicemia, hypokalemia, weight gain and rhabdomylosis (muscle destruction determined by the increased energy consumption and by the depletion of the muscular deposits of glycogen).

The metabolic correlations established between the body's hormonal mechanisms will also affect the reproductive organs leading to amenorrhea or oligomenorrhea, infertility, difficulty conceiving and recurrent miscarriages. In men, gynecomastia may occur.