Other causes of hyperthyroidism include multinodular goiter, toxic solitary nodules of the thyroid, and functioning thyroid cancer. Struma ovarii is another rare cause of hyperthyroidism. All of the latter conditions cause increased thyroid radioactive iodine uptake on scanning. Symptoms of Graves' disease are those of hyperthyroidism and may include anxiety, restlessness, irritability, emotional instability, fatigue, muscle weakness or cramps, increased appetite, palpitations and heat intolerance. Patients may also have a fast heart beat, atrial fibrillation, tremor, an eye stare and changes in hair.
Osteoporosis tends to occur if hyperthyroidism left untreated.
There may also be increased sweating and increased numbers of bowel movements, shortness of breath on exertion and weight changes. Usually there is weight loss, but occasional patients gain weight ironically due to an increased appetite. Periodic paralysis with low potassium may occur in men who are of Asian, Filipino, or Native American ethnic backgrounds. Menstrual irregularities and cardiac angina are also common. Additionally, with Graves' disease there is usually a goiter.