title: Augmentation of growth hormone secretion in children with constitutional growth delay by short term clonidine administration: a pulse amplitude-modulated phenomenon.
abstract: We evaluated the effect of chronic clonidine administration on 24-h integrated GH secretion (IC-GH) in eight children (six boys and two girls; age, 6.0-13.0 yr) with constitutional growth delay (CGD). Clonidine was given orally in a daily dose of 0.1 mg/m2 at bedtime for 6 months; 24-h secretion studies were performed before and after 2 months of treatment. Clonidine caused a significant augmentation (P less than 0.02) of mean IC-GH from 2.6 +/- 0.4 (+/- SE) to 4.6 +/- 0.6 micrograms/L. The increase in IC-GH was mainly the result of increased GH pulse amplitude, which rose from 12.3 +/- 1.3 to 18.2 +/- 2.1 micrograms/L (P less than 0.01). The mean GH pulse amplitude was significantly higher (P less than 0.02) during sleep (15.9 +/- 2.4 micrograms/L) than during the awake hours (8.4 +/- 1.5 micrograms/L) before treatment. During clonidine treatment the mean GH pulse amplitude during the awake hours (15.0 +/- 3.8 micrograms/L) was similar to that during sleep (20.3 +/- 3.1 micrograms/L). GH pulse frequency was not altered by treatment during either the awake or sleep hours. The mean insulin-like growth factor I levels after 2 (1400 +/- 300 U/L) and 6 (1760 +/- 430 U/L) months of treatment were significantly higher (P less than 0.02 and P less than 0.05, respectively) than the pretreatment value (920 +/- 240 U/L). After 2 months of clonidine treatment, growth velocity increased from 3.1 +/- 0.5 to 10.2 +/- 1.0 cm/yr (P less than 0.001), and after 6 months of treatment is was still significantly higher (7.0 +/- 0.7 cm/yr; P less than 0.02) than that before treatment. These results confirm the ability of clonidine to accelerate growth in children with CGD and indicate that clonidine is capable of increasing IC-GH levels. They also reinforce the view that many children with CGD have decreased endogenous GH secretion.
authors.affiliation: Department of Pediatrics, University of Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Loche
authors.forename: R
authors.initials: R
authors.lastname: Puggioni
authors.forename: T
authors.initials: T
authors.lastname: Fanni
authors.forename: S G
authors.initials: SG
authors.lastname: Cella
authors.forename: E E
authors.initials: EE
authors.lastname: Müller
authors.forename: C
authors.initials: C
authors.lastname: Pintor
mesh_terms: D001827:Body Height; D002648:Child; D003000:Clonidine / Q000008:administration & dosage / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D005260:Female; D006130:Growth Disorders / Q000188:drug therapy*; D013006:Growth Hormone / Q000097:blood* / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000097:blood; D008297:Male
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D003000:Clonidine