Endocrine Abstracts

Objectives: The goal of this study was to evaluate the value of a TRH stimulation test to assess the risk of permanent central hypothyroidism after transsphenoidal pituitary surgery.

Methods: A retrospective cohort study was performed, evaluating the results of a routinely performed TRH stimulation test executed in the first 2 weeks after transsphenoidal pituitary surgery in patients admitted to the Ghent University Hospital between 1/1/2010 and 31/12/2019. The presence of central hypothyroidism was evaluated 6-18 months post-surgery by extracting the diagnosis from the patient file, combined with double checking based on the presence of T4 substitution therapy and corresponding thyroid function tests within this timeframe.

Results: After exclusion of patients with central hyperthyroidism and patients who received additional radiotherapy within the first 18 months after the surgery, 116 patients were included, 18 of whom developed permanent central hypothyroidism. Permanent postoperative central hypothyroidism was significantly associated with a low TSH at the start of the TRH stimulation test, as well as with a low maximum TSH and a low maximum TSH increase from baseline after TRH administration. A peak TSH of<2.0 mU/l during the test had a sensitivity of 100% and a specificity of 87.2% to identify patients at risk for permanent central hypothyroidism.

Conclusions: Our data support the use of a postoperative TRH stimulation test with a cut-off value of 2.0mU/l as maximum reached TSH value during the test as a screening tool to identify patients at risk of permanent central hypothyroidism after transsphenoidal pituitary surgery.