Evidence for an altered tryptophan metabolism in fibromyalgia.

Neurobiol Dis 2002 Dec;11(3):434-42

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

Psychiatric Hospital, University of Munich, D-80336, Munich, Germany

PMID: 12586552


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.