Effect of Thyrotropin-Releasing Factor in Man

This study reports the changes of plasma TSH levels which occurred when a highly purified preparation of porcine TRF was given to 3 cretins. These results in man indicate a certain lack of species specificity since TRF prepared from the hypothalami of pigs was active in the mouse and rat as well as man. The levels of TSH were measured by both bioassay and radioimmunoassay and were found to rise within 3 min in 2 of the patients and by 6 min in all 3 patients. The greatest rise was from 6 to 30 min and was followed by a gradual decline of the TSH level over the next 45 min. When the plasma level of TSH was measured in one of the patients 120 min after injecting TRF, it had returned to the base line level. Some conditions considered important for testing the activity of TRF in man are given. Because of the limited supply of TRF available, it was not possible to determine if the above were the optimal conditions for detecting the TRF response in man.