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

Plasma and urine glycosaminoglycans (GAGs), long linear sulfated polysaccharides, have been 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 (or GAGome), a reference study of the normal healthy GAGome is currently missing. Here, we prospectively enrolled 270 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. Free GAGomes did not correlate with age nor with any of the 25 blood chemistry biomarkers, except for a few plasma disaccharides that correlated with hemoglobin and C-reactive protein. However, free GAGome levels were generally higher in males. Partitioned by gender, we established reference ranges for all plasma and urine free chondroitin sulfate (CS), heparan sulfate (HS), and hyaluronic acid (HS) disaccharides. Our study is the first large-scale determination of normal plasma and urine free GAGomes reference ranges and represents a critical resource for biomarker research.