Objectives: To evaluate plasma amino acid (AA) concentrations in patients affected by fibromyalgia (FM) and to study the relationships between their levels and FM clinical parameters.
Design and methods: 20 AAs were assessed in 34 FM patients and in 18 healthy volunteers by means of a modified version of the Waters picotag method.
Results: Significant lower plasma taurine, alanine, tyrosine (Tyr), valine, methionine, phenylalanine and threonine concentrations, and the sum of essential AAs were observed in FM patients vs healthy controls (P<0.05). Tyr CAA' ratio and the sum of AAs competing with tryptophan for brain uptake were significantly reduced in FM (P<0.05). A significant correlation was found between FM clinical parameters and certain AAs.
Conclusions: Our results suggest probable defects of gut malabsorption of certain AAs in FM patients. Moreover, given the reduced Tyr CAA' ratio in FM patients, a possible impairment of the cathecolaminergic system in the FM syndrome may be suggested.