TRH and TSH-secreting pituitary adenoma: Although not routinely used in the U.S. outside the academic setting, approximately 90% patients with RTHβ had normal or increased (similar to hypothyroid) TSH responses to TRH stimulation (200 μg bolus intravenously, sampling at 0, 20, 60, 90 and 120 min) whereas patients with TSHomas typically had high basal levels and only 39% responded to TRH [36, 41].