Management strategies for TSH secreting pituitary adenomas (TSHomas)
B Patel, E Hatfield, G Das, N Mendoza, K Meeran, Imperial College Healthcare NHS Trust, Ashford and St Peterís Hospitals NHS Foundation Trust
Background: TSHomas are rare, and our limited experience can result in diagnostic and treatment challenges. Here we describe two cases to highlight how individualising patient management can lead to successful outcomes.
Case 1: A 35-year-old lady presented with amenorrhoea following discontinuation of the oral contraceptive pill. After a single progesterone challenge, she fell pregnant and successfully breastfed, however her amenorrhoea persisted. She also noted increased tiredness, anxiety and palpitations. Her main desire at the time was pregnancy. She is otherwise fit and well, not taking any regular medications, and there is no family history of thyroid problems. She was clinically euthyroid with no evidence of eye disease or goitre, and visual fields were intact to confrontation.
Initial work-up showed raised thyroid hormones (FT4 29 pmol/L[NR 9-23] and FT3 13.8 pmol/L [NR 2.5-5.7]) with unsuppressed TSH (5.4 milliunit/L [NR 0.3-4.2]). There was no evidence of co-secretion of other pituitary hormones. The abnormality persisted despite excluding assay interference and non-thyroidal illness; and central hyperthyroidism was suspected. An MRI demonstrated a pituitary macroadenoma (17 mm), with excavation of the sellar floor and extension into the suprasellar space, but no contact with the optic chiasm. Markers of peripheral thyroid action including sex hormone binding globulin and alpha-glycoprotein subunit were raised. Dynamic testing revealed a blunted response to thyrotropin releasing hormone.
The results were discussed at the Pituitary Multidisciplinary meeting, and a diagnosis of TSHoma was made with a plan for surgical removal. To optimise thyroid function pre-operatively, lanreotide was administered; however, a single dose induced intolerable diarrhoea, and hence it was discontinued. Surgery was performed successfully 8 weeks later; however, her diarrhoea persisted, and she was admitted with hyponatraemia. The differentials included hypovolaemia, post-op diabetes insipidus and cortisol deficiency.† Although she was treated temporarily with fluids and hydrocortisone, it was felt her diarrhoea was due to the recent lanreotide. Her post-op pituitary hormone axes were preserved, and there was no residual tumour on MRI. Her menses have returned and she remains well off hormone replacement.
Case 2: A 65-year-old lady with confirmed TSHoma in 2002, declined surgery in view of her neuropathy and reduced mobility related to underlying Charcot-Marie-Tooth disease. As a consequence, she was commenced on monthly octreotide LAR injections (20mg subcutaneously). Her baseline TFTs were: TSH 3.5 milliunit/L, FT4 20.9pmol/L and FT3 12.8 pmol/L. Within two years of treatment, the tumour had shrunk in size and she was rendered euthyroid.† Her annual follow up remained unremarkable with no side effects, and normal liver function. In 2008, she developed type 2 diabetes (HbA1C 6.9%) and was commenced on oral therapy. She has responded well to octreotide for nearly 18 years and her latest TFTs are: TSH 2.83 milliunit/L, FT4 17.1 pmol/L and FT3 3.1 pmol/L.