Endocrine Abstracts

Objective: To report the unusual presentation of a thyrotropinoma in a patient with: i) accelerated bone turnover, evident as osteopenia and increased serum alkaline phosphatase level, and ii) a pericardial effusion, years before diagnosis, that resolved completely following surgery and somatostatin analogue treatment.

Case report: A 38-year-old man had been treated for years for presumed hypothyroidism with thyroxine supplementation based on elevated TSH levels before the clinical suspicion of a TSH secreting pituitary adenoma (TSHoma) was raised. During that time period there was a persistent elevation of alkaline phosphatase and associated osteopenia that had been attributed to vitamin D deficiency, although vitamin D supplementation was of no benefit. He concurrently developed a pericardial effusion of no apparent cause despite a comprehensive diagnostic work up and was treated surgically. Recurrence of a pericardial effusion and a pleural effusion developed a few months after initial treatment. At that time thyroxine was discontinued, a pituitary macroadenoma was diagnosed and TSHoma was confirmed by classical biochemical features and an elevated a-glycoprotein subunit. After surgery, due to incomplete resection and persistent although mild elevation of a-glycoprotein subunit, an octreoscan was performed and, based on a positive scan, treatment with octreotide long acting repeatable (LAR) was initiated, to which he had an antitumor and antisecretory response. Shortly after initiation of medical treatment a recession of the pericardial effusion was noted and alkaline phosphatase levels were normalized.

Conclusion: Increased bone metabolism due to a hyperthyroid state induced by a TSHoma may be anticipated. However, effusions (pericardial, pleural) have only rarely been reported in combination with hyperthyroidism. To our knowledge this is the first case of a TSHoma accompanied by pericardial and pleural effusions that both dissolved after treatment of the adenoma.