Thyrotropin-releasing hormone stimulation test in patients with pituitary pathology.

Objectives: To evaluate the value of the thyrotropin-releasing hormone (TRH) stimulation test in the diagnostic work-up of the thyroid function in patients with pituitary pathology.

Methods: To compare the thyrotropin (TSH) response and the absolute and fold changes after TRH administration in 35 patients with pituitary pathology and 26 normal subjects.

Results: Nine of the patients and 2 of the normal subjects had a pathological response. No difference in the thyrotropic response to TRH was found either for the actual values, or for the absolute or fold changes of TSH between the groups.

Conclusion: The role of the TRH test in the evaluation of thyroid function in patients with pituitary pathology is modest. The best variables for evaluation of the presence of central hypothyroidism are still a free thyroxine estimate combined with an inappropriately low TSH.