Dependency of growth hormone (GH) stimulation following releasing hormones on the spontaneous 24-hour GH secretion in healthy male and female subjects

Abstract

The purpose of this investigation was to evaluate whether in healthy subjects the GH response following stimulation with releasing hormones is dependent on the spontaneous GH secretion within 24 hr prior to the stimulation test. In 18 male and 9 female healthy subjects (21-59 years) GH was measured every 15 min over 26 hr. Twenty-four hours after the beginning of blood sampling, a GH stimulation test was performed by using a combined releasing hormone test. Sleep was recorded in three consecutive nights. A positive correlation was found between the AUCs of the 24-hr GH secretion and the AUCs of GH stimulation, which could not be explained by an age effect only. This study demonstrates that subjects with comparatively high amounts of GH secreted within 24 hr also show good GH secretory responses when immediately after the 24-hr sampling period a stimulation test is undertaken. Therefore, a low GH response to stimulation cannot be explained by feedback effects of high GH amounts secreted during the 24 hr before the test or by empty pituitary GH storages.