Circadian and ultradian characteristics of plasma growth hormone in children with normal and short stature
Hermida, R.C.; Garcia, L.; Lodeiro, C.; Ayala, D.E.; Iglesias, T.; Halberg, F.
Journal of Endocrinological Investigation 12(8 Suppl 3: 69-73
1989
ISSN/ISBN: 0391-4097 PMID: 2509542 Document Number: 341505
Circadian and ultradian variations characterize plasma growth hormone (GH) in 40 boys and 10 girls of short stature, and 15 boys and girls of normal stature, 6-14 yr of age, living on a diurnal waking (approximately 07:00 to approximately 22.00), nocturnal resting routine. Blood was drawn at about 3-h intervals during a 24-h span and serum stored frozen at -60 degrees C until radioimmunoassay for GH concentration. A linear least-squares spectrum analysis of those data reveals the anticipated statistically significant circadian rhythm as the principal spectral feature for all groups. Prominent components with a period of 12 h were also found for the groups of short boys and short girls, and of 8 h for short boys. A parameter comparison indicates similar circadian characteristics between short and normal children, whether one compares boys (p = .52, .30 and .84 for comparison of rhythm-adjusted means (M), amplituedes (A) and acrophases (phi), respectively), girls (p = .65, .37 and .92), or all children (p = .53, .31 and .87). These results notwithstanding, studies of GH responses to GH-releasing hormone in children with short stature and healthy controls should be extended to evaluate any possible difference in terms of gender and circadian or ultradian timing.