Endocrine Abstracts

Introduction: Thyroid-stimulating hormone-secreting pituitary adenomas (TSH-omas) are infrequent, constituting 0.5%-3.0% of pituitary adenomas (PAs). Additionally, the co-secretion of growth hormone (GH) and TSH in PAs is notably rare, accounting for only 16% to 19.7% of TSH-producing PAs. Limited cases have been reported.

Observation: We report the case of a 59-year-old woman who presented with asthenia and weight loss; she was referred to the endocrinology department for further investigation as a dysmorphic syndrome suggestive of acromegaly was noted. She had no previous medical or surgical history. On physical examination she has an enlargement of hands and feet, enlarged tongue and thickened lips, enlarged and protruding mandible. Blood pressure was 130/80 and pulse was 65 bpm. Laboratory results showed: IGF-1, 397.9 ng/ml; non-suppressible GH levels after oral glucose loading; free thyroxine (FT4), 61.47 pmol/l (12-22 pmol/l); TSH, 0.41 μU/ml. Adrenocorticotropic hormone (ACTH), <1.5 ng/l; cortisol 918.4 nmol/l; follicle stimulating hormone (FSH), 22.72 mU/l; PRL, 116 mUI/l; estradiol, 26 pg/ml; Alpha subunit was 0,87 mUI/ml with elevated α-TSH/TSH molar ratio at 3.48. Magnetic resonance imaging showed a macroadenoma measuring 10 mm × 11 mm. The patient was prescribed 30 mg of methimazole. Follow-up thyroid assessments one month later indicated a TSH level of 0.19 mIU/ml and an FT4 level of 44.07 pmol/l. After restoring FT4 to normal levels, a transsphenoidal excision surgery for the pituitary adenoma is planned.

Conclusion: This is a rare case of a pituitary macroadenoma producing both GH and TSH. This may be due to the fact that Pit-1-producing cells have been shown to be the source of both somatotrophs and thyrotrophs during differentiation into mature pituitary cells. Early diagnosis, multidisciplinary management and vigilant surveillance are essential to improve the prognosis of this co-secreting PAs.