Category: Pituitary Disorders/Neuroendocrinology
TSH-secreting pituitary adenomas are among the less prevalent pituitary tumors, corresponding to 0.9-1.5% of all pituitary adenomas and often go undiagnosed for several years.
A 36 year old female with hypertension initially presented with amenorrhea, abnormal thyroid function tests and elevated prolactin. She complained of a two-year history of palpitations, elevated resting heart rate, shortness of breath, fatigue, decreased left upper visual field, fifteen pound weight gain, diarrhea, heat intolerance, dizziness, hearing loss, ankle swelling, anxiety, easy bruising and facial hair. Free thyroxine (2.8ng/dL) and free triiodothyronine (6.6 pg/mL) were elevated along with an inappropriately high normal value of TSH (4.03 uIU/mL) consistent with TSH-secreting pituitary adenoma. Alpha subunit was also elevated to 13 ng/ml. MRI brain confirmed a pituitary adenoma. Patient underwent a transsphenoidal resection. Pathology stains showed the pituitary tumor cells were positive for prolactin and negative for ACTH, GH, FSH, LH and TSH.
The initial treatment of a TSH-secreting pituitary adenoma is medical therapy with somatostatin analogs to restore euthyroidism prior to surgery. Once euthyroid, transsphenoidal resection of the tumor is the most appropriate definitive therapy for patients with TSH-secreting pituitary adenomas. Methimazole long-term can make these tumors grow, but since our patient had visual field defects the plan was to operate as soon as possible, therefore treatment with methimazole was short-term. Her TSH, free thyroxine and free triiodothyronine postoperatively fell to 0.024 iIU/ml, 1.08 ng/dl and 1.67 pg/ml, respectively. The patient felt an improvement in her vision after surgery and her symptoms improved 1 month after discharge.
Discussion : TSH-secreting pituitary adenomas account for much less than 1 percent of all cases of hyperthyroidism. The biological activity of the TSH that is secreted varies considerably and as a result, serum immunoreactive TSH concentrations range from normal (albeit inappropriately high in the presence of hyperthyroidism) to markedly elevated. They exhibit positive immunostaining for alpha subunit and TSH-beta in up to 75% of cells only.
Despite the hallmark feature of central hyperthyroidism, TSH secreting adenomas often are inappropriately treated as primary hyperthyroidism and thus diagnosis can be much delayed.
Arpita Bhalodkar– Endocrinology Fellow, Northwell Health- Lenox Hill Hospital, new york, New York
Natalie Cusano– Endocrinology Attending, Lenox Hill, Northwell, new york, New York
Phillip Bukberg– Endocrinology Attending, Lenox Hill, Northwell, new york, New York
Northwell Health- Lenox Hill Hospital
new york, New York
Arpita Bhalodkar is endocrinology fellow at Lenox Hill Hospital in NYC. She is in her first year of fellowship. She went to NYIT for her Bachelors in Science and AUA for medical school. She trained in Bronx Lebanon hospital for residency in Bronx, NY.
Lenox Hill, Northwell
new york, New York
Dr. Natalie Cusano, Endocrinology/Metab/Diabetes - American Board of IM/Endo, Diabetes, Metabolism