Neurobiology of Disease (Dec 2002)

Evidence for an Altered Tryptophan Metabolism in Fibromyalgia

  • M.J. Schwarz,
  • M. Offenbaecher,
  • A. Neumeister,
  • T. Ewert,
  • M. Willeit,
  • N. Praschak-Rieder,
  • J. Zach,
  • M. Zacherl,
  • K. Lossau,
  • R. Weisser,
  • G. Stucki,
  • M. Ackenheil

Journal volume & issue
Vol. 11, no. 3
pp. 434 – 442

Abstract

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Fibromyalgia (FM) is a prevalent syndrome with chronic pain and a hypothesized underlying disturbance of the tryptophan (TRP) metabolism. We performed a tryptophan depletion (TD) test in 17 FM patients and 17 controls. TRP, 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), and interleukin-6 (IL-6) were measured. Additionally pain perception was monitored in the FM patients. FM patients and controls exhibited a decrease of TRP and KYN during TD. 5-HIAA levels also decreased in all controls and in 11 FM patients, but showed a marked increase in 6 FM patients. IL-6 significantly increased during TD in the patients, but not in the controls. Pain perception was not affected in the FM patients. These data demonstrate an altered TRP metabolism in a subgroup of FM patients, where the TD seems to activate 5-HT metabolism. Our findings may have diagnostic as well as therapeutic implications in the field of fibromyalgia.