title: Growth hormone response to arginine test differentiates between two subgroups of Huntington's disease patients.
abstract: OBJECTIVE
  Huntington's disease (HD) is an autosomal dominant disorder characterised by motor, cognitive and psychiatric disturbances. Several studies have demonstrated that hypothalamic dysfunction is part of the phenotypic spectrum. The aim of the study was to evaluate the growth hormone (GH) response to arginine infusion in a cohort of HD patients, to search for an in vivo biomarker of hypothalamic dysfunction.
  
  
  METHODS
  The authors investigated 17 HD patients and 17 age-, sex- and BMI-matched healthy controls. Clinical assessment of patients was performed using the Unified Huntington's Disease Rating Scale motor section and total function capacity. Metabolic and endocrine investigations included total, LDL and HDL cholesterol, basal insulin, GH, insulin-like growth factor 1 (IGF-1), SD Score IGF-1 (SDS IGF-1) and the GH response to arginine stimulation.
  
  
  RESULTS
  HD patients showed lower plasma IGF-1 and SDS IGF-1 levels and a higher baseline GH in comparison with control subjects. The arginine test induced a normal GH peak in nine patients (53%; Arg+), whereas the response was absent in the remaining eight (47%; Arg-). Arg+ and Arg- also showed two distinct endocrine/metabolic profiles with differences in insulin and lipid metabolism.
  
  
  CONCLUSIONS
  It remains to be clarified if these two subgroups of patients, according to the GH response to arginine, correspond to different disease stages or to different patterns of neurodegeneration.
authors.affiliation: Dipartimento di Scienze Neurologiche, Università degli Studi di Napoli Federico II, Naples, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Salvatore
authors.forename: Carlo
authors.initials: C
authors.lastname: Rinaldi
authors.forename: Tecla
authors.initials: T
authors.lastname: Tucci
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Maio
authors.forename: Carolina
authors.initials: C
authors.lastname: Di Somma
authors.forename: Silvia
authors.initials: S
authors.lastname: Savastano
authors.forename: Gaetano
authors.initials: G
authors.lastname: Lombardi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Filla
authors.forename: Annamaria
authors.initials: A
authors.lastname: Colao
authors.forename: Giuseppe
authors.initials: G
authors.lastname: De Michele
mesh_terms: D000328:Adult; D000368:Aged; D001120:Arginine / Q000494:pharmacology*; D016022:Case-Control Studies; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D019382:Human Growth Hormone / Q000097:blood* / Q000502:physiology; D006801:Humans; D006816:Huntington Disease / Q000097:blood / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D001120:Arginine