Introduction Discovery of biomarkers predictive of endotheliopathy after hematopoietic stem cell transplant (HSCT) has the potential to more rapidly identify vulnerable patients, guide treatment decisions, track responses to therapy, and inform targets for novel treatment. This study aimed to evaluate the levels and predictive capabilities of glycocalyx biomarkers for endotheliopathy in the first 100 days following HSCT in pediatric and young adult patients. Methods Parallel prospective observat