Correlation between circulating plasma glycocalicin and sitosterol levels. Plasma glycocalicin in sitosterolemia patients was analyzed using a sandwich enzyme-linked immunosorbent assay that employs 2 different mAbs against human GPIbα. The Scientific and Standardization Committee/International Society on Thrombosis and Haemostasis Secondary Coagulation Standard was assigned as 1 U/mL and used to construct a standard curve.