Endocrine Abstracts

Background: Among the disorders causing hyperthyroidism thyrotropin-secreting pituitary adenomas (TSH-omas) are extremely rare and account for <2% of all pituitary adenomas. Failure to recognize a TSH-oma may lead to improper therapy attempts and dramatic consequences. We have reported a patient that wrongly had diagnosed and treated as primary hyperthyroidism for fifteen years.

Case: A 50 years old woman who was on the treatment of propilhyourasil (150 mg/day) referred our endocrinology clinic from physichiatry clinic due to high serum thyroid-stimulating hormone (TSH), free thyroxine (fT₄) and free triiodothyronine (fT₃) levels. She was complaining of sweating and shortness of breathing. Physical examination revealed slightly enlarged thyroid gland but were otherwise unremarkable. Laboratory investigations revealed TSH level of 5.15 (n:0.27–4.2) mU/l, fT₄ level of 2.78 (n:0.9–1.7) ng/dl and free T₃ level of 6.2 (n:1.8–4.6) pg/ml. The serum alfa-subunit level was 0.84 (n<0.90) IU/l and alfa-subunit: TSH molar ratio was 1.63 (n<1). There was impaired TSH response to TRH stimulation and no supression of TSH with T₃ supression test. An MRI scan revealed 20 mm adenoma in the right side of the pituitary gland. These biochemical and radiological investigations were consistent with the diagnosis of TSH-oma. We have planed to attempt neurosurgical removal after a course of medical treatment with octreotide LAR 20 mg/month for a period of 3–6 months. After 3 months on the octreotide treatment all of TSH, fT₄ and fT₃ levels have decreased (3.09 mU/l, 2.20 ng/dl, 4.78 pg/ml respectively). On MRI scan adenom has regressed to 17 mm in diameter.

Conclusion: In a patient with high levels of tyroid hormones if TSH level is high or normal TSH-oma must be suspected. Misdiagnosed TSH-oma patients undergo wrong treatments and due to persistant hyperthyroidism physichosomatic symptoms may get them to physiciatry clinics. Neurosurgical treatment may be first choice after restoration of thyroid state with octreotide treatment.