• When you have a hyperactive thyroid, your body produces too much of a hormone called thyroxine. This condition is called hyperthyroidism and it can cause you to experience many unpleasant symptoms. Some of these symptoms can become quite serious if your overactive thyroid is left untreated. With accurate diagnosis followed by proper treatment, hyperthyroidism can be successfully controlled.
  
  

Symptoms

• The symptoms of a hyperactive thyroid are wide ranging because thyroxine affects many bodily systems. You may have trouble concentrating and become irritable, nervous or restless. You might have an increased appetite, yet have unexplained weight loss. Other hyperthyroidism symptoms include increased sweating, intolerance to heat, trembling, fatigue, insomnia, diarrhea, nausea, skin flushing and generalized itching.
  
  Cardiac symptoms are common with a hyperactive thyroid and these could become serious. You may develop a rapid heart rate and irregular heart rhythm. Your heart may feel like it is pounding in your chest.
  
  

Signs

• Physical signs of hyperthyroidism include the development of a goiter, or enlarged thyroid gland, and Grave's opthalmopathy which is the appearance of protruding eyes. Both of these signs can be detected by your doctor upon a physical examination. Grave's opthalmopathy develops in people with hyperactive thyroids because swelling occurs behind the eyes that causes the eyes to push forward. This can also cause the eyes to have blurry vision and become more sensitive to light. It could even limit normal eye movement.
  
  The medical signs of a hyperactive thyroid include blood tests that are positive for increased levels of thyroxine and decreased levels of thyroid stimulating hormone, or TSH. The level of TSH is important in diagnosing hyperthyroidism because it is the hormone responsible for stimulating the thyroid to produce thyroxine. When TSH levels are low it indicates the amount of circulating thyroxine is higher than it should be. Follow-up thyroid testing might include a thyroid scan and a radioactive iodine uptake test. The radioactive iodine uptake test measures how quickly your thyroid collects iodine. The more thyroxine your thyroid produces, the quicker the iodine is collected.
  
  

Precautions

• It is important not to ignore the signs and symptoms of a hyperactive thyroid. According to the Mayo Clinic, you could develop serious complications, like congestive heart failure, atrial fibrillation and osteoporosis if your hyperthyroidism is left untreated.