Introduction: Thyrotropinomas are rare pituitary tumour accounting for 0.51.0% of all pituitary tumours. There are only seven reported cases of mixed TSH/LH/FSH producing adenoma. We report a patient with secondary hyperthyroidism due to TSH producing adenoma co-secreting FSH and LH.
Case report: A 75-year-old Caucasian male was seen with 2-year history of tiredness, anxiety and palpitations along with 7-month history of weight loss. He also complained of impotence for 2 years along with lack of sex drive. His thyroid function tests showed fT4 level of 55.1 pmol/l along with TSH level of 8.3 mU/l and anti TPO antibodies of 7 IU/ml. His other anterior pituitary tests were: FSH 3.7 IU/l, LH 3.0 IU/l, IGF1 <3.2 nmol/l and prolactin level of 389 mU/l. His alpha Sub Unit came back high at 1.95 IU/l and pituitary MRI showed a 1.8 by 2.5 cm lesion in the pituitary gland compressing the right optic nerve and invading the right cavernous sinus. He was started on octeotride LAR 60 mg along with carbimazole 30 mg once daily and following discussion in pituitary MDT meeting was referred for trans-sphenoidal pituitary surgery. Following pituitary surgery his TFT came back as fT4 of 26.2 pmol/l with TSH of 3.3 mU/l. Biopsy of the lesion confirmed mixed TSH/LH/FSH producing adenoma.
Discussion: Thyrotropinomas are rare with a prevalence of about one case/million. Most cases are found in the fifth-sixth decade of life. Around 30% of TSH producing adenoma also co-secrete other pituitary hormones most commonly GH and prolactin. Majority of thyrotropinomas are macroadenomas (90%) and clinical features of hyperthyroidism are usually present. Definite treatment consists of pituitary surgery though octeotride therapy lead to normalization of thyroid hormones in about 70% of cases with partial shrinkage of tumour in 40% of thyrotropinomas.