Different Correlation Patterns Between Circulating Amino Acids and Body Temperature in Fibromyalgia Syndrome: A Cross-Sectional Study.

The aim of this study was to analyze the association between circulating amino acids and central and peripheral body temperature in subjects with and without fibromyalgia syndrome (FMS). A total of 47 patients with FMS and 59 healthy subjects were included in the study. The concentration of amino acids was determined in serum samples using a fluorimeter coupled with a high-performance liquid chromatography system. An infrared thermography camera was used to estimate peripheral hand temperatures. The core temperature of the body was estimated using an infrared thermometer, which was applied to the axillary and tympanic areas. Correlations between several thermographic variables of the hands and tryptophan, methionine, 3-methylhistidine, histidine, glutamic acid, and tyrosine were identified exclusively within the FMS group. In contrast, correlations between aminoadipic acid and serine and thermographic variables were observed only in the healthy control group. The concentrations of asparagine and lysine correlated with thermographic variables in both groups. The essential amino acid leucine was found to correlate with axillary temperature in FMS patients. However, it should be noted that the observed associations between aminoadipic acid and tryptophan blood concentrations and axillary temperature were limited to the control group. Several correlations were identified between circulating amino acids and different body temperatures in both healthy controls and patients with FMS. However, the correlation pattern differs significantly between FMS patients and healthy controls. These findings suggest the possibility of a change in the function of several amino acids in the thermoregulatory process in patients with FMS.