Endocrine Abstracts

Introduction: Thyrotropin-secreting pituitary tumors (TSH-omas) are a rare disorder and an infrequent cause of hyperthyroidism. The prevalence in the general population being 1 to 2 cases per million. However, recents studies have demonstrated an increase of TSH-omas over time. The increased number of cases principally results from the ultrasensitive TSH immunometric assays and from improved general practioner endocrinologist awaress. There is an inappropriate secretion of TSH due to autonomous and refractory to the negative feedback of thyroid hormones. In about 30% of patients with pituitary adenomas, hypersecretion of other pituitary hormones can be detected. The most frequent associations are the hypersecretion of GH and/or PRL.

Clinical case: A 28-year-old woman attended the emergency room by left hemicranial headache after accidental head injury in a soccer match. Pituitary MRI found a pituitary macroadenoma (18.5×25×31.5 mm). There are no symptoms of amenorrhea or galactorrhea. She also didn’t complain of symptoms of tachycardia, tremor or weight loss. She didn’t refer changes in shoe or ring size. On examination, there is no goiter or other stigmata of endocrine dysfunction. Laboratory evaluations showed central hyperthyroidism (FT3 6.85 pg/ml, FT4 1.98 ng/dl, TSH 6.66 mU/l), circulating free alpha-GSU elevation (> 9 mUi/l), insulin-like growth factor elevation (IGF-1 237 ng/ml) and hyperprolactinemia (PRL pool 64.97 ng/ml). TRH stimulation test was performed and TSH and alpha-GSU levels didn’t increase after TRH injection. GH nadir concentrations after 75 mg oral glucose tolerance test (OGTT) was ≥1 μg/l. Therefore, hypersecretion of thyrotropin and GH was confirmed. Hyperprolactinemia was attributed to pituitary stalk compression. The patient was prescribed the somatostatin analogues (somatuline autogel 60 mg every 28 days). After 1 month of treatment, IFGF-1 level decreased to 180 ng/ml and normalitation thyroid function (FT3 2.48 pg/ml, FT4 0.97 ng/dl, TSH 2.48 mU/l). Somatuline autogel dose was titrated up to 120 mg every 60 days. After 3 months of treatment, tumor size has been reduced (18×19×16 mm). A transnasal adenoidectomy was performed with restoration of euthyroidism and normalization of IGF1 and PRL levels. Preserved pituitary function after surgery resection. The pathological anatomy showed positive cells for synaptophysin, CAM 5.2 TSH and GH.

Conclusions: TSH-omas are rare pituitary tumors but the use of ultrasensitive immunoassay methods and the increase in imaging tests allow early diagnosis. Treatment with somatostatin analogues may be useful to reduce hyperthyroid signs and symptoms, as well as the adenoma size.