Increased plasma bilirubin in Parkinson patients on L-dopa: Evidence against the free radical hypothesis?

G. Scigliano, F. Girotti, P. Soliveri, M. Musicco, D. Radice, T. Caraceni

Research output: Contribution to journalArticlepeer-review


Oxidative damage by free radicals may contribute to the etiology of Parkinson's disease (PD), and increased oxidative stress in the nigral cells of PD patients may occur following L-dopa treatment, prompting suggestions that L-dopa therapy should be delayed as long as possible. Bilirubin is a potent antioxidant in vitro, even when bound to albumin, suggesting a physiological role as an antioxidant. Calculations indicate that bilirubin can pass the blood-brain barrier in sufficient quantity to exert a significant antioxidant effect in the brain. We have found a highly significant (about 20%) increase in plasma bilirubin in 162 PD patients on chronic L-dopa treatment compared to 93 untreated parkinsonians and 224 non-parkinsonian controls. We propose that L-dopa-induced increase in nigral oxidative stress in PD may be effectively counteracted by increased bilirubin levels. The mechanism by which plasma bilirubin is increased in patients receiving L-dopa is at present unknown.

Original languageEnglish
Pages (from-to)69-72
Number of pages4
JournalItalian Journal of Neurological Sciences
Issue number2
Publication statusPublished - 1997


  • bilirubin
  • free radicals
  • L-dopa
  • Parkinson's disease

ASJC Scopus subject areas

  • Dermatology
  • Clinical Neurology
  • Psychiatry and Mental health
  • Neuroscience(all)


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