Impaired Prolactin Response to Synthetic Thyrotropin-Releasing Hormone After a 36 Hour Fast

Abstract

Nine male patients 35 to 60 years old received 100 µg synthetic thyrotropin-releasing hormone (TRH) after both an overnight and a 36 hour fast and the serum prolactin response was measured by radioimmunoassay. The prolonged fast significantly (p < 0.05) decreased the mean peak prolactin response from 86.3 ± 25.9 to 32.0 ± 6.2 and the increment above basal from 76.8 ± 24.3 to 27.5 ± 5.5 ng/ml. There was no change in the pattern or timing of the response and basal values were insignificantly lowered. These observations are discussed in relation to the effects of fasting on glucose, insulin, growth hormone, free fatty acid, ketones and water and electrolyte metabolism.