Endocrine Abstracts

Introduction: Thyrotropin secreting pituitary adenomas are rare constituting <2% of pituitary adenomas. Thirty percent of these tumors may be plurihormonal. Most common cosecreted hormone is GH and the least one is PRL. We report here a case of plurihormonal pituitary adenoma symptomatic for TSH secretion.

Case report: A 35-year-old female admitted to hospital because of fatigue, heat intolerance, headache, galactorrhea and menstrual irregularity. Her laboratory analysis showed hyperprolactinemia (PRL: 74 ng/ml), and high fT₃ level with inappropriately normal TSH (TSH: 3.14 μIU/ml (n: 0.27–4.2 μIU/ml) fT₃: 4.67 pg/ml (n: 1.96–4.36), fT₄: 1.24 ng/ml (n: 0.72–1.56 ng/dl). GH level was also high but IGF1 levels were all normal and she did not have any signs or symptoms of acromegaly. Pituitary MRI showed 18×15 mm macroadenoma extending to suprasellar region. She was followed-up with cabergolin for a year. Then she had transsphenoidal hypophysectomy. The immunohistochemical staining showed that tumor cells were strongly reactive to GH, PRL and TSH; Ki67 index was 2%. Four months after operation, she got pregnant. There was no biochemical abnormality during pregnancy. Her pituitary MRI didn’t show any residual image. But at postpartum 2 months, high fT₃ and fT₄ levels were revealed. PRL was 60 ng/dl (analysis was done 4 h after breastfeeding), fT₃: 4.39 pg/ml, fT₄: 1.66 ng/dl, TSH: 2.33 μIU/ml, GH: 2.09 ng/ml, IGF1: 205 ng/ml (n: 109–284), cortisol was suppressed after dexamethasone suppression test (1.57 μg/dl). Physical examination revealed only tachycardia. Thyroid autoantibodies were all negative. Thyroid USG was normal other than a 5.3 mm heterogenous, isoechoic nodule. SHBG, glycoprotein alpha subunit to TSH ratio were normal. But TSH levels failed to increase after TRH stimulation test. A pituitary adenoma 16×12×12 mm extending to optic chiasm, invading bilateral cavernous sinuses was found on MRI. Visuel field was normal. Octreotide LAR 20 mg/month and propranolol 40 mg/day were started and reoperation has been planned.

Conclusion: This case emphasizes that all pituitary adenomas should be screened for secretion of all hormones and immunohistochemical staining of all pituitary hormones is mandatory for correct classification.