Analysis of Normal Levels of Urine and Plasma Free Glycosaminoglycans in Adults

Abstract

Plasma and urine glycosaminoglycans (GAGs) are long linear sulfated polysaccharides recognized as potential non-invasive biomarkers for several diseases. However, owing to the analytical complexity associated with the measurement of GAG concentration and disaccharide composition, the so-called GAGome, a reference study of the normal healthy GAGome is currently missing. Here, we prospectively enrolled 308 healthy adults and analyzed their urine and plasma free GAGomes using a standardized ultra-high-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UHPLC-MS/MS) method together with comprehensive demographic and blood chemistry biomarker data. Of 25 blood chemistry biomarkers, we mainly observed weak correlations between the free GAGome and creatinine in urine, and hemoglobin or erythrocyte counts in plasma. We found higher free GAGome concentration - but not composition - in males. Partitioned by gender, we established reference intervals for all detectable free GAGome features in urine and plasma. We carried out a transference analysis in healthy individuals from two distinct geographical sites, including the Lifelines Cohort Study, which validated the reference intervals in urine. Our study is the first large-scale determination of normal plasma and urine free GAGomes reference intervals and represents a critical resource for physiology and biomarker research.