title: Long-term patterns of urinary pyroglutamic acid in healthy humans.
abstract: An investigation of human biological variation in urinary organic acids, including pyroglutamic acid along with 39 other compounds, was previously reported in which levels were determined for 8 weeks in healthy adult subjects. Here, unique, 4-week-long physiological trends for one of those compounds, pyroglutamic acid (PGA), are reported. When PGA levels for an individual rose above 40 μg/mg creatinine, 4-week downward progressions occurred until levels reached values near 15 μg/mg creatinine and the pattern was reversed when levels for an individual were below that level in the early weeks of the study. The pattern was especially prominent among 8 of the 13 menstruating female subjects suggesting a possible association with metabolic stress of the menstrual cycle. However, it also appeared in 3 of the 8 male subjects where other sources of metabolic stress may be present. The menstrual association is consistent with estrogen-mediated increase in oxidative stress. Since PGA is linked to glutathione turnover, the consistency of extreme values across all individuals displaying the pattern indicates that 15 and 40 μg/mg creatinine may represent limits that trigger shifts in sulfur amino acid metabolism. This is the first observation of approximate month-long cyclic responses in a glutathione-related urinary marker in humans.
authors.affiliation: NGA Bioscience, Waleska, Georgia rslord22@icloud.com.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Lord
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D011761:Pyrrolidonecarboxylic Acid / Q000652:urine*
chemical_list: D015415:Biomarkers; D011761:Pyrrolidonecarboxylic Acid
keywords: 5‐oxoproline; Pyroglutamic acid; glutathione; physiological cycles