Assessment of nitric oxide, advanced oxidation protein products, malondialdehyde, and thiol levels in patients with restless legs syndrome

Sleep Med. 2012 Apr;13(4):414-8. doi: 10.1016/j.sleep.2011.11.012.


Objectives: We aimed to determine the importance of oxidative stress in the pathogenesis of restless legs syndrome (RLS) by quantification of advanced oxidation protein products and total thiol levels (as markers of oxidative protein damage), nitric oxide levels (as an antioxidant and endothelial function), and malondialdehyde levels (as a marker of lipid peroxidation) in patients with RLS.

Design and methods: A total of 22 patients with primary RLS were enrolled in the study and 20 age-and-gender-matched healthy subjects were enrolled as a control group. Serum nitric oxide, malondialdehyde, thiol levels, and plasma advanced oxidation protein products levels were determined by spectrophotometric methods.

Results: Serum nitric oxide and thiol levels were lower in the patient group than in controls (p = 0.007 and p = 0.017, respectively). Plasma advanced oxidation protein products levels and serum malondialdehyde levels were found to be higher in patients with RLS than in controls (p = 0.017 and p = 0.008, respectively). Serum malondialdehyde level was found to be positively correlated with plasma advanced oxidation protein products levels (p = 0.039). Serum thiol level was found to be negatively correlated with plasma advanced oxidation protein products levels (p = 0.030).

Conclusions: Increased advanced oxidation protein products, malondialdehyde levels, and decreased thiol and nitric oxide levels, may suggest that patients with RLS are under oxidative stress. Although both lipid peroxidation and protein oxidation may have a role in atherosclerosis in RLS, those factors may be related to the pathogenesis of RLS.

MeSH terms

  • Adult
  • Biomarkers / blood
  • Female
  • Humans
  • Lipid Peroxidation / physiology*
  • Male
  • Malondialdehyde / blood*
  • Middle Aged
  • Nitric Oxide / blood*
  • Oxidative Stress / physiology*
  • Restless Legs Syndrome / etiology
  • Restless Legs Syndrome / metabolism*
  • Sulfhydryl Compounds / blood*


  • Biomarkers
  • Sulfhydryl Compounds
  • Nitric Oxide
  • Malondialdehyde