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What are the causes of thyrotoxicosis ?

Thyrotoxicosis is defined as the state of thyroid hormone excess. 
But it is not synonymous with hyperthyroidism, which is the result of excessive thyroid function.
Following are the causes of thyrotoxicosis
  • Primary hyperthyroidism 
  • Thyrotoxicosis without hyperthyroidism
  • Secondary hyperthyroidism 
1. Primary hyperthyroidism
Graves' disease.
Toxic multinodular goiter.
Toxic adenoma.
Functioning thyroid carcinoma metastases.
Activating mutation of the TSH receptor.
Activating mutation of Gs alpha (McCune-Albright syndrome.  Struma ovarii ).
Drugs-iodine excess.
2.Thyrotoxicosis without hyperthyroidism
Subacute thyroiditis. 
Silent thyroiditis.
Other causes of thyroid destruction are amiodarone, radiation, infarction of adenoma.
Ingestion of excess thyroid hormone (thyrotoxicosis factitia) or thyroid tissue.
3.Secondary hyperthyroidism
TSH-secreting pituitary adenoma. 
Thyroid hormone resistance syndrome. 
Chorionic gonadotropin-secreting tumors.
Gestational thyrotoxicosis.