title: Multiple system atrophy is distinguished from idiopathic Parkinson's disease by the arginine growth hormone stimulation test.
abstract: OBJECTIVE
  Multiple system atrophy (MSA) may be difficult to distinguish from idiopathic Parkinson's disease (PD). Our aim was to evaluate the accuracy of the arginine growth hormone (GH) stimulation test in distinguishing between MSA and PD in large populations of patients.
  
  
  METHODS
  We measured the GH response to arginine in 69 MSA (43 MSAp [parkinsonism as the main motor feature] and 26 MSAc [cerebellar features predominated]) patients, 35 PD patients, and 90 healthy control subjects. We used receiver-operating curve analysis to establish the arginine cutoff value that best differentiated between MSA and PD.
  
  
  RESULTS
  The GH response to arginine was significantly lower (p < 0.01) in MSA than in either PD patients or control subjects. At a cutoff level of 4 microg/L, arginine distinguished MSAp from PD with a sensitivity and specificity of 91% and MSAc from PD with a sensitivity of 96% and specificity of 91%. The arginine test had a positive predictive value for MSA of 95%. The GH response to arginine was not affected by disease duration or severity, MSA motor subtype, pyramidal signs, response to dopaminergic therapy, or magnetic resonance imaging findings.
  
  
  CONCLUSIONS
  The GH response to arginine differentiates MSA from PD with a high diagnostic accuracy. The results suggest an impairment of cholinergic central systems modulating GH release in MSA.
authors.affiliation: Departments of Neurological Sciences, University of Naples "Federico II," Naples.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Pellecchia
authors.affiliation: Departments of Neurological Sciences, University of Naples "Federico II," Naples.
authors.forename: Katia
authors.initials: K
authors.lastname: Longo
authors.affiliation: Departments of Molecular and Clinical Endocrinology and Oncology, University of Naples "Federico II," Naples.
authors.forename: Rosario
authors.initials: R
authors.lastname: Pivonello
authors.affiliation: Department of Neurosciences, University of Pisa, Pisa.
authors.forename: Claudio
authors.initials: C
authors.lastname: Lucetti
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics, University of Genoa, Genoa.
authors.forename: Roberta
authors.initials: R
authors.lastname: Marchese
authors.affiliation: Department of Neurology, Misericordia Hospital, Grosseto.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Spampani
authors.affiliation: Neurology Unit, Poliambulanza Hospital, Brescia.
authors.forename: Michela
authors.initials: M
authors.lastname: Manfredi
authors.affiliation: Department of Neuroscience, Psychiatry and Anesthesiology, University of Messina, Messina.
authors.forename: Antonio
authors.initials: A
authors.lastname: Epifanio
authors.affiliation: Department of Clinical Neurosciences, S. Anna University Hospital, Ferrara.
authors.forename: Mariachiara
authors.initials: M
authors.lastname: Sensi
authors.affiliation: Department of Neuroscience, University of Padua, Padua.
authors.forename: Tomaso
authors.initials: T
authors.lastname: Scaravilli
authors.affiliation: Department of Neuroscience, University of Padua, Padua.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Bracco
authors.affiliation: Department of Clinical Neurosciences, S. Anna University Hospital, Ferrara.
authors.forename: Roberto
authors.initials: R
authors.lastname: Eleopra
authors.affiliation: Department of Neuroscience, Psychiatry and Anesthesiology, University of Messina, Messina.
authors.forename: Letterio
authors.initials: L
authors.lastname: Morgante
authors.affiliation: Neurology Unit, Poliambulanza Hospital, Brescia.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Donati
authors.affiliation: Department of Neurology, Misericordia Hospital, Grosseto.
authors.forename: Roberto
authors.initials: R
authors.lastname: Marconi
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics, University of Genoa, Genoa.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Abbruzzese
authors.affiliation: Department of Neurosciences, University of Pisa, Pisa.
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Bonuccelli
authors.affiliation: Department of Neurosciences, University of Catania, Catania, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Zappia
authors.affiliation: Departments of Molecular and Clinical Endocrinology and Oncology, University of Naples "Federico II," Naples.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Colao
authors.affiliation: Departments of Neurological Sciences, University of Naples "Federico II," Naples.
authors.forename: Paolo
authors.initials: P
authors.lastname: Barone
mesh_terms: D000978:Antiparkinson Agents / Q000627:therapeutic use; D001120:Arginine / Q000494:pharmacology; D003937:Diagnosis, Differential; D005260:Female; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis*; D010300:Parkinson Disease / Q000175:diagnosis* / Q000188:drug therapy; D012372:ROC Curve; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents; D019382:Human Growth Hormone; D001120:Arginine