Clinical and biochemical characteristics of patients with thyroid-stimulating hormone-secreting pituitary adenomas from one New Zealand centre

Background: Thyroid-stimulating hormone (TSH)-secreting pituitary adenomas (TSHoma) are a rare cause of thyrotoxicosis and need to be distinguished from the syndrome of resistance to thyroid hormone. Patients with TSHoma may also be misdiagnosed as having primary hyperthyroidism and receive inappropriate treatment directed towards the thyroid gland. Methods: We performed a retrospective review of patients with TSHoma who presented to one New Zealand endocrine service between 1989 and 2003. Results: Six patients with TSHoma were managed during this time period. All patients had elevated free thyroid hormone levels with elevated, or inappropriately normal, TSH levels. The median age at presentation was 43 years and the median time from symptom onset to correct diagnosis was 3 years (range 0.25-12 years). Five patients had a macroadenoma at the time of diagnosis. Three had been treated elsewhere for primary hyperthyroidism prior to referral. Three patients received octreotide as primary treatment with two of these patients later undergoing transsphenoidal resection of the pituitary adenoma. Conclusion: With increased awareness and earlier diagnosis of TSH-secreting pituitary adenomas, management can be appropriately directed towards the pituitary.