title: Acute decrease in serum testosterone after a mixed glucose and protein beverage in obese peripubertal boys.
abstract: OBJECTIVE
  Delayed puberty and lower levels of testosterone (T) have been observed in adult obese males and some adolescent males. In adult men, enteral glucose ingestion results in acute lowering of serum testosterone levels; however, this has not been studied in adolescents. We aimed to examine the acute effect of a glucose/protein beverage on serum T concentration changes in obese peripubertal males. A second objective was to determine whether change in T concentration was related to appetite hormone levels.
  
  
  METHODS
  Twenty-three overweight and obese males aged 8-17 in pre-early (Tanner stage 1-2) and mid-late (Tanner stage 3-5) puberty were included in this cross-sectional study at the Clinical investigative unit at the Hospital for Sick Children. Participants consumed a beverage containing glucose and protein, and blood samples measuring pubertal hormones, ghrelin and glucagon-like peptide-1 (GLP-1) were taken over 60 min.
  
  
  RESULTS
  Across pubertal stages, there was a significant decrease in T levels in adolescent boys (-18·6 ± 3·1%, P < 0·01) with no proportional differences between pre-early and mid-late puberty (P = 0·09). Decrease in T was associated with a decrease in LH (r = 0·52, P = 0·02), and fasting T was inversely correlated with fasting ghrelin (r = -0·51, P = 0·03) with no correlation with GLP-1.
  
  
  CONCLUSIONS
  Intake of a mixed glucose/protein beverage acutely decreases T levels in overweight and obese peripubertal boys. A potential mechanism for this decrease may be secondary to an acute decrease in LH, but this requires further evaluation.
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.|Division of Endocrinology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: Schwartz
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Barkha P
authors.initials: BP
authors.lastname: Patel
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: Shirley
authors.initials: S
authors.lastname: Vien
authors.affiliation: Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: G Harvey
authors.initials: GH
authors.lastname: Anderson
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.|Division of Endocrinology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Jill
authors.initials: J
authors.lastname: Hamilton
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001628:Beverages; D002648:Child; D003430:Cross-Sectional Studies; D005215:Fasting / Q000097:blood; D054439:Ghrelin / Q000097:blood; D052216:Glucagon-Like Peptide 1 / Q000097:blood; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D011627:Puberty / Q000097:blood* / Q000502:physiology; D013739:Testosterone / Q000097:blood*; D000067816:Whey Proteins / Q000008:administration & dosage*
chemical_list: D054439:Ghrelin; D000067816:Whey Proteins; D013739:Testosterone; D052216:Glucagon-Like Peptide 1; D007986:Luteinizing Hormone; D005947:Glucose