Abstract
Synthetic thyrotropin-releasing factor (TRF), L-pyroglutamyl-L-histidyl-L-proline amide, has been administered intravenously to the cases with primary hypothyroidism, thyrotoxicosis and patients receiving desiccated thyroid powder in doses ranging from 30 to 50 mg. Changes in plasma TSH levels, PBI and T3 resin sponge uptake (T3RSU) were estimated. TRF in doses of 50-200 μg stimulates a rapid rise in plasma TSH in all of the normal subjects. No rise in plasma TSH level occurred following 100 Jag of TRF in patients receiving desiccated thyroid powder. Primary hypothyroidism showed high resting TSH levels and exaggerated TSH response to TRF, 2 types of TRF that induced TSH response were observed in 26 cases with untreated thyrotoxicosis. The one was blunted TSH response and the other was suboptimal TSH response to TRF. When thyrotoxic patients became enthyroid state following treatment, almost normal TSH response were observed after TRF administration except a few cases with longstanding thyrotoxicosis.
