Simultaneous study of cortisol, growth hormone and prolactin nyctohemeral variations in normal and obese subjects. Influence of prolonged fasting in obesity

Abstract

Hourly integrated concentrations (IC) of growth hormone (GH), prolactin (PRL) and cortisol were determined by a continuous sampling procedure in six obese women, before and at the end of a 12 day fast, and in eight normal controls under basal conditions. Hormonal 24 h IC and nyctohemeral variations were calculated from these data. Nyctohemeral rhythms were investigated by the periodogram method. A significant increase over basal values of 24 h IC of PRL, GH and cortisol was observed at the end of the fasting period. Nyctohemeral variations--but not nyctohemeral rhythm--of IC-GH were found in normal subjects. They were abolished in obese patients under basal conditions but restored during fasting. The circadian rhythm of cortisol was not altered in obesity. A shift of the normal nyctohemeral rhythm of PRL was observed in obese patients, but the normal pattern was restored during fasting.