title: Increased serum insulin-like growth factor 1 in early idiopathic Parkinson's disease.
abstract: OBJECTIVE
  Insulin-like growth factor 1 (IGF-1) provides protection against loss of dopaminergic neurons in animal models of Parkinson's disease (PD). The aim of this study was to measure serum IGF-1 in patients with PD and assess its correlation with the clinical presentation.
  
  
  METHODS
  Serum IGF-1 and growth hormone (GH) levels were measured in 12 patients with idiopathic PD and 12 matched healthy controls, three times over a period of 6 months after overnight fasting. Based on the results, serum IGF-1 was measured in six additional, yet untreated, PD patients.
  
  
  RESULTS
  IGF-1 values were stable over the whole period (r=0.83-0.93) in patients and controls. IGF-1 was significantly higher in treated PD patients than in controls at all time points (all p<0.001). There were no significant differences in serum GH levels between patients and controls. Receiver operating characteristics showed a cut-off at 114 ng/ml for differentiation of treated patients and controls (area under the curve=0.90). In the patient group, higher serum IGF-1 levels were correlated with shorter disease duration (r=-0.56, p=0.001). In the healthy control group, higher IGF-1 was correlated with slightly impaired motor performance, as measured by the Unified Parkinson's Disease Rating Scale motor score (r=0.46, p=0.005). In the untreated patient group, serum IGF-1 levels were significantly higher than in healthy controls (p<0.001). Applying the cut-off value of 114 ng/ml, all untreated patients were correctly classified as PD patients.
  
  
  CONCLUSIONS
  Increased IGF-1 might be an interesting serum marker for early PD and potentially for subclinical dopaminergic dysfunction.
authors.affiliation: Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, Hoppe-Seyler-Str 3, D-72076 Tübingen, Germany. jana.godau@medizin.uni-tuebingen.de
authors.forename: Jana
authors.initials: J
authors.lastname: Godau
authors.forename: Manon
authors.initials: M
authors.lastname: Herfurth
authors.forename: Barbara
authors.initials: B
authors.lastname: Kattner
authors.forename: Thomas
authors.initials: T
authors.lastname: Gasser
authors.forename: Daniela
authors.initials: D
authors.lastname: Berg
mesh_terms: D000368:Aged; D015415:Biomarkers; D015331:Cohort Studies; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood*; D010865:Pilot Projects
chemical_list: D015415:Biomarkers; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I