Effect of menopause on circulating amino acid concentrations in women with fibromyalgia and healthy women.

OBJECTIVES

Fibromyalgia is a complex syndrome that appears more frequently during menopause. No previous studies have investigated the effect of menopause on amino acids in women with fibromyalgia. Therefore, we have examined serum amino acid concentrations in premenopausal and postmenopausal women with fibromyalgia and healthy women.

STUDY DESIGN

A case-control study was carried out in 28 premenopausal and 46 postmenopausal healthy women and in 16 premenopausal and 52 postmenopausal women with fibromyalgia. This study adheres to STROBE guidelines.

MAIN OUTCOME MEASURES

Amino acid content was assayed using high-performance liquid chromatography.

RESULTS

Significant differences were found in concentrations of several amino acids (aspartic acid, glutamic acid, histidine, glycine, alanine, leucine, and taurine) between healthy premenopausal women and premenopausal women with fibromyalgia and between healthy postmenopausal women and postmenopausal women with fibromyalgia. Concentrations of other amino acids (aminoadipic acid, asparagine, threonine, arginine, 5-methyl-histidine, valine, methionine, isoleucine, phenylalanine, ornithine, branched-chain amino acids, large neutral amino acids, essential amino acids, non-essential amino acids, basic amino acids, and arginine/ornithine ratio) were found to differ between healthy postmenopausal women and postmenopausal women with fibromyalgia, but not between healthy premenopausal women and premenopausal women with fibromyalgia. No significant differences were found in serum amino acid concentrations between premenopausal and postmenopausal healthy women or between premenopausal and postmenopausal women with fibromyalgia.

CONCLUSIONS

Our results show, for the first time, that the association between menopause and fibromyalgia may increase the risk of metabolic disorders by disrupting amino acid homeostasis to a greater extent than menopause or fibromyalgia alone.