BACKGROUND Systemic capillary leak syndrome (SCLS) (Clarkson's disease) is a rare disorder of unknown etiology, characterized by transient episodes of hypotension, and the microvascular leak of fluids into the peripheral tissues, resulting in edema. Between 80-90% of patients with SCLS have a concomitant monoclonal gammopathy. Although translational in vitro studies have implicated vascular endothelial barrier dysfunction in the etiology of SCLS, the etiology and disease associations in clinical cases remain unknown. CASE REPORT We report a case of SCLS in a 49-year-old woman who initially presented with an upper respiratory tract infection, which was complicated by edema and compartment syndromes in the extremities that required fasciotomies. Serum levels of the cell surface heparan sulfate proteoglycan, syndecan-1 (CD138), a measure of endothelial surface glycocalyx (ESG) damage, were measured by enzyme-linked immunoassay (ELISA), peaked at up to 500 ng/mL (reference range, 50-100 ng/mL) and normalized on disease remission. CONCLUSIONS This case report supports the view that damage to the microvascular endothelium, has a role in the pathogenesis of acute SCLS. This case also indicated that monitoring serum levels of syndecan-1 (CD138) might be used to monitor the progression and resolution of episodes of SCLS.