Thyrotoxicosis not associated with hypehyroidism is caused by all Except

Thyrotoxicosis is a hypermetabolic state caused by elevated circulating levels of free T3 and T4. Hypehyroidism is hyperfunction of the thyroid gland. Hypehyroidism is the most common cause of thyrotoxicosis, however, in ceain conditions, the oversupply is related to either excessive release of preformed thyroid hormone (e.g., in thyroiditis) or to an extrathyroidal source, rather than hyperfunction of the gland (Struma ovarii, exogenous intake)In TSH-secreting pituitary adenoma, TSH will stimulate the thyroid, so its secondary hypehyroidism.Robbins pathology Pg: 1083