title: Increased plasma/serum levels of prolactin in multiple sclerosis: a meta-analysis.
abstract: OBJECTIVE
  Prolactin (PRL) is a polypeptide hormone that is known to stimulate humoral and cell mediated immune responses. PRL levels have been investigated in several autoimmune diseases including multiple sclerosis (MS); however, these have yielded different and inconsistent results. This study aims to perform a more precise evaluation on the plasma/serum PRL levels in MS patients, and to explore the available influential factors.
  
  
  METHODS
  Research related to plasma/serum PRL levels in MS patients and healthy controls were gathered using PubMed, EMBASE and The Cochrane Library database (until Mar 31 2016). Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by fixed-effects or random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I2, and publication bias was evaluated using a funnel plot and Egger's linear regression test.
  
  
  RESULTS
  516 articles were obtained after searching databases, and 8 studies with 426 MS patients and 296 controls were finally included. Meta-analysis revealed that, compared with the control group, the MS group had significantly higher plasma/serum PRL levels, with the SMD of 0.55 and 95%CI (0.39, 0.72). Subgroup analyses showed that region, age and disease duration were associated with PRL level in MS patients.
  
  
  CONCLUSIONS
  In summary, our meta-analysis revealed a significantly higher PRL level in MS patients than healthy controls, and it is influenced by region, age and disease duration.
authors.affiliation: a Department of Pediatrics , the First Affiliated Hospital of Anhui Medical University , Hefei , China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: b Department of Microbiology and Parasitology, Anhui Key Laboratory of Microbiology and Parasitology , Anhui Medical University , Hefei , China.
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.affiliation: c Department of Clinical Laboratory , the First Affiliated Hospital of Anhui Medical University , Hefei , China.
authors.forename: Zhong-Le
authors.initials: ZL
authors.lastname: Cheng
authors.affiliation: a Department of Pediatrics , the First Affiliated Hospital of Anhui Medical University , Hefei , China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
mesh_terms: D000367:Age Factors; D006801:Humans; D009103:Multiple Sclerosis / Q000097:blood*; D011388:Prolactin / Q000097:blood*; D013997:Time Factors
chemical_list: D011388:Prolactin
keywords: MS; Multiple sclerosis; hormone; meta-analysis; prolactin