title: Dynamic changes of growth hormone-binding protein concentrations in normal men and patients with acromegaly: effects of short-term fasting.
abstract: Plasma concentrations of growth hormone (GH) and GH-binding protein (GHBP) were measured at hourly intervals in five healthy men and five patients with acromegaly during the fed state and after a 5-day fast. GHBP concentrations (both total and complexed with endogenous GH) were analyzed by the ligand-mediated immunofunctional assay (LIFA). Total GHBP was similar in both groups during the fed state (104.4 +/- 5.2 and 101.6 +/- 10.3 pmol/L), did not exhibit a diurnal rhythm, and was unchanged by fasting (91.9 +/- 5.4 and 109.9 +/- 10.5 pmol/L, respectively). However, the GHBP/GH complex concentration was significantly higher in acromegalics than in controls (41.0 +/- 2.8 v 18.0 +/- 2.2 pmol/L, respectively; P < .05), closely followed diurnal GH rhythm in normals, and was significantly correlated with mean 24-hour GH concentrations (r = .86, P < .01). We conclude that plasma concentrations of GHBP are stable throughout the day and are unchanged either by short-term calorie deprivation or by chronic exposure to high levels of endogenous GH. In contrast, GHBP/GH complex concentrations are altered both acutely and chronically by ambient GH.
authors.affiliation: Department of Medicine, Veterans Affairs Medical Center, Ann Arbor, MI, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ho
authors.forename: N
authors.initials: N
authors.lastname: Gesundheit
authors.forename: W L
authors.initials: WL
authors.lastname: Wong
authors.forename: S H
authors.initials: SH
authors.lastname: Huang
authors.forename: R D
authors.initials: RD
authors.lastname: Friberg
authors.forename: A L
authors.initials: AL
authors.lastname: Barkan
mesh_terms: D000172:Acromegaly / Q000097:blood*; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002352:Carrier Proteins / Q000097:blood*; D015331:Cohort Studies; D004435:Eating; D005215:Fasting; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D002352:Carrier Proteins; D013006:Growth Hormone; C051815:somatotropin-binding protein