Nocturnal release of immunoreactive growth hormone-releasing hormone and growth hormone in normal children.

To evaluate the role of growth hormone-releasing hormone (GHRH) in the physiologic release of growth hormone (GH) we studied the nocturnal secretion of immunoreactive GHRH (ir-GHRH) and its relationship to GH release and various stages of sleep in six prepubertal (three boys) and six pubertal children (two boys) with normal stature. Their ages ranged from 8.1 to 14.9 yr and their bone ages from 6.8 to 14.8 yr. Blood was withdrawn continuously between 2200-0600 h at a constant rate of 5 mL/20 min. The EEG was simultaneously registered. The ir-GHRH and GH data were analyzed by a discrete-pulse detection algorithm (Pulsar). The number of nocturnal ir-GHRH pulses varied from 0-8 (median 7) and the number of GH peaks from 2-6 (median 3). Pubertal children had significantly more (p less than 0.05) ir-GHRH pulses and the pulse amplitude was higher (p less than 0.05) than in the prepubertal children. There were no significant differences in the GH parameters between the two groups. The ir-GHRH peaks were not significantly related to any specific sleep stage. The majority of the GH pulses (71%) were associated with slow wave sleep (p less than 0.001). Two-thirds (69%) of the GHRH peaks preceded closely or coincided with GH pulses (p less than 0.02). Pubertal subjects had more isolated ir-GHRH peaks than prepubertal children (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)