Background There is strong evidence of mitochondrial dysfunction in both familial and sporadic Parkinson’s disease (PD). A biomarker reliably identifying mitochondrial dysfunction would be particularly important for future stratified/personalized medicine trials in Parkinson’s disease. A previous comparison of serum biomarkers in mitochondrial disease established that serum growth differentiation factor 15 (GDF-15) outperforms fibroblast growth factor-21 (FGF-21) and distinguishes patients with mitochondrial diseases from those without them.

Objective To systematically assess GDF-15, FGF-21 and mitochondrial DNA copy number (mtDNA) levels in the serum of patients with sporadic PD and controls to determine their utility as a suitable mitochondrial biomarker panel for PD.

Methods 120 patients with PD and 102 age-matched controls were recruited from a single centre. GDF-15, FGF-21 and mtDNA copy number were quantified using previously established assays.

Results FGF-21 concentrations did not significantly differ between groups. GDF-15 serum levels were significantly raised in late onset PD compared to controls and early onset PD. There was no difference in mtDNA between groups. None of the biomarkers tested showed a significant association with disease following multivariate logistic regression analysis.

Conclusion Serum FGF-21, GDF-15 and blood mtDNA could not accurately differentiate between PD and controls when assessed as candidate biomarkers.