title: A case of thyrotropin-secreting pituitary microadenoma with normal thyrotropin alpha-subunit level.
abstract: We present a 32-year-old male with a thyrotropin (TSH)-secreting pituitary microadenoma with normal alpha-subunit (SU) and/or alpha-SU/TSH molar ratio. An interesting feature of this patient is that the size of the pituitary tumor remained unchanged during a 6-year follow-up without treatment. The tumor was clearly visualized with somatostatin receptor imaging, indicating that it was somatostatin receptor-positive. Subcutaneous injection of 100 microg octreotide acetate three times daily resulted in significant reduction of TSH and free thyroid hormones 6 weeks after initiation of treatment. However, tumor size was not changed 3 months after initiation of octreotide therapy and thyroid hormones, but not TSH level, eventually increased in spite of increasing the octreotide dosage up to 600 microg/day. This led to discontinuation of treatment. The patient responded only temporarily to octreotide in spite of somatostatin receptors. This case further demonstrates that a normal alpha-SU and/or alpha-SU/TSH molar ratio cannot exclude the possibility of a TSH-secreting pituitary adenoma.
authors.affiliation: Department of Endocrinology & Metabolism, Gulhane School of Medicine, Etlik-Ankara, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Ozata
authors.forename: E
authors.initials: E
authors.lastname: Oztürk
authors.forename: Y
authors.initials: Y
authors.lastname: Narin
authors.forename: C
authors.initials: C
authors.lastname: Tayfun
authors.forename: O
authors.initials: O
authors.lastname: Azal
authors.forename: Z
authors.initials: Z
authors.lastname: Beyhan
authors.forename: A
authors.initials: A
authors.lastname: Corakçi
authors.forename: H
authors.initials: H
authors.lastname: Bayhan
authors.forename: M A
authors.initials: MA
authors.lastname: Gündoğan
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging / Q000378:metabolism*; D000328:Adult; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood*; D006728:Hormones / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D015282:Octreotide / Q000008:administration & dosage / Q000627:therapeutic use; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin / Q000378:metabolism; D013963:Thyroid Hormones / Q000097:blood; D013972:Thyrotropin / Q000378:metabolism*
chemical_list: D015292:Glycoprotein Hormones, alpha Subunit; D006728:Hormones; D017481:Receptors, Somatostatin; D013963:Thyroid Hormones; D013972:Thyrotropin; D015282:Octreotide