Glycocalyx shedding as a clinical biomarker in critical illness

The endothelial glycocalyx, a carbohydrate-rich layer lining the vascular endothelium, plays a critical role in maintaining vascular homeostasis by regulating permeability, leukocyte adhesion, and inflammatory signaling. Its degradation has been implicated in endothelial dysfunction and organ damage in various diseases. Biomarkers derived from glycocalyx components, particularly Syndecan-1 (SDC-1) and heparan sulfate (HS), can be detected in blood and urine, providing a potential window into vascular injury. In this narrative review, we explore the clinical potential of glycocalyx-derived biomarkers, with a focus on SDC-1, in a broad spectrum of conditions, including sepsis, coronavirus disease, acute respiratory distress syndrome, kidney diseases, cardiovascular disorders, autoimmune diseases, cancer, trauma, and pregnancy-related complications. We highlight the pathophysiological mechanisms of glycocalyx degradation, assess the diagnostic and prognostic utility of SDC-1, and summarize emerging therapeutic strategies to preserve glycocalyx integrity. Given their strong association with disease severity and outcomes, glycocalyx-derived biomarkers may enable earlier diagnosis, improved risk stratification, and personalized treatment, supporting more informed clinical decision-making across diverse medical conditions.