Hyperthyroidism Causes

• Grave's disease: This thyroid condition results from abnormal stimulation of the thyroid gland by a material in the blood termed the thyroid stimulating immunoglobulin (TSI). TSI overstimulates the thyroid causing a goiter. It also causes Grave's eye disease, including a "bug-eyed" look and "frightened stare." This can progress to severe eye pain or eye muscle weakness causing tearing and double vision. It also causes raised, thickened skin over the shins or tops of the feet. 
  
  
• Toxic multinodular goiter: This occurs when part of the thyroid gland produces thyroid hormones all by itself, without regard to TSH stimulation. It usually occurs in people with a long-standing goiter, usually in the elderly. Toxic multinodular goiter is different from Grave's disease because of the general lack of eye complications and less severe signs of hyperthyroidism. 
  
  
• Thyroiditis: This inflammatory disorder of the thyroid gland includes such conditions as de Quervain's thyroiditis or Hashimoto's thyroiditis. In these conditions, you may have periods of increased thyroid hormone release due to the inflammation, causing a hyperthyroid state. As thyroid failure occurs due to the inflammatory response, hypothyroidism may occur. 
  
  
• Pituitary adenoma: This tumor of the pituitary gland causes independent TSH production leading to overstimulation of the thyroid gland. 
  
  
• Drug-induced hyperthyroidism: This is most commonly caused the heart medication amiodarone (Cordarone). It may be prevented by monitoring this possible side effect and weighing them against the benefits of using this heart medication.