title: Complex rhythmicity of growth hormone secretion in humans.
abstract: To better characterize the 24 hr GH secretion pattern in humans, we studied frequently sampled 24 hr GH profiles in 93 young (18-45 years of age) healthy, fed volunteers: men (n=67) and women (n=26) with BMI<26 kg/m(2). Analysis of the composite GH series in men revealed 3 significant GH "waves" with peaks occurring at midnight (p<0.0001), at noon (p<0.02) and at 1800 h (p<0.0001). In women, similar pattern was seen, with three GH "waves" peaking at midnight (p<0.0001), 1100 h (p<0.02) and at 1600 h (p<0.002). We conclude that the 24 hr rhythmicity of GH secretion is far more complex than currently appreciated. The attribution of the two daytime GH "waves" to food consumption is unlikely but cannot be excluded at the present time. The complex temporal pattern of pulsatile GH secretion may have important effects on regulation of target cell function.
authors.affiliation: Department of Internal Medicine, Division of MEND, University of Michigan Medical Center and Department of Veterans Affairs Hospital, Ann Arbor, MI 48109, USA.
authors.forename: Sowmya
authors.initials: S
authors.lastname: Surya
authors.forename: Kathleen
authors.initials: K
authors.lastname: Symons
authors.forename: Edward
authors.initials: E
authors.lastname: Rothman
authors.forename: Ariel L
authors.initials: AL
authors.lastname: Barkan
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000378:metabolism*; D012727:Sex Characteristics
chemical_list: D013006:Growth Hormone