Usually pituitary hyperthyroidism refers to hyperthyroidism due to overproduction of thyrotropin-releasing hormone secreted by the pituitary gland. When the pituitary gland is diseased for various reasons, including pituitary tumors or pituitary hyperplasia, it may cause the pituitary gland to secrete too much TSH (thyroid-stimulating hormone), which in turn causes the thyroid gland to secrete too much T3 (triiodothyronine) and T4 (thyroxine), leading to secondary hyperthyroidism. Laboratory tests for hyperthyroidism will show elevated TSH, T3, and T4, accompanied by an abnormal MRI of the pituitary gland. The treatment of pituitary hyperthyroidism is different from that of simple hyperthyroidism and requires surgical intervention or radiotherapy to the pituitary gland. It is recommended to consult an endocrinologist for treatment of pituitary hyperthyroidism.