von Willebrand factor antigen (VWFAg) and ADAMTS13 antigen (ADAMTS13Ag) levels in plasma in a cohort of 35 patients with acute TMA. Normal ranges are indicated by dashed lines (50 to 100 UI/dL for VWFAg and 740 to 1420 ng/mL for ADAMTS13Ag). Each TMA patient is represented by a circle. All but 3 patients exhibited a VWFAg level higher than 100 IU/dL, while all but 3 patients had a decreased ADAMTS13Ag level. Statistical analysis showed no correlation between VWFAg and ADAMTS13Ag levels.