Serum iron levels and Parkinson’s disease risk: evidence from a meta-analysis

Background: Whether the serum iron level in Parkinson’s disease (PD) patients was higher than those in health controls was not consistent in the reported studies. Thus, we conducted a meta-analysis to summarize the evidence from observational studies between them. Methods: Pertinent studies were identified by a search in PubMed and Web of Knowledge up to July 2015. Standardized mean difference (SMD) was performed to combine the results. Random-effect model was used. Publication bias was estimated using Egger’s regression asymmetry test. Results: In our study, ten articles involving 591 PD cases and 917 health controls were included in the analysis. Our pooled results suggested that PD patients had a significantly higher serum iron levels compared with those in health controls [summary SMD = 0.28, 95% CI = 0.16, 0.39, P<0.001]. The associations were also significant both in Europe [SMD = 0.60, 95% CI = 0.37, 0.83] and in Asia population [SMD = 0.48, 95% CI = 0.32, 0.65]. No publication bias was found. Conclusions: The current study suggested that serum iron level in PD patients was significantly higher than those in health controls, both in Europe and Asia populations.