Increased serum insulin-like growth factor 1 in early idiopathic Parkinson's disease
- Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, University of Tübingen, Tübingen, Germany
- Correspondence to Dr J Godau, Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, Hoppe-Seyler-Str 3, D-72076 Tübingen, Germany;
- Received 17 February 2009
- Revised 27 April 2009
- Accepted 5 May 2009
- Published Online First 22 February 2010
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.
Conclusion Increased IGF-1 might be an interesting serum marker for early PD and potentially for subclinical dopaminergic dysfunction.
Competing interests None.
Ethics approval This study was conducted with the approval of the ethics committee of the University of Tuebingen.
Provenance and peer review Not commissioned; externally peer reviewed.