Markers of contact and intrinsic pathway activation are elevated in patients with SCD compared with that in healthy controls. Plasma from healthy controls (n = 23) and patients with SCD (n = 53) was assayed for (A) FXIIa-C1INH, (B) FXIa:C1INH, (C) PKa:C1INH, and (D) FIXa-AT complexes. Data are presented as mean ± SEM and analyzed by Student t test. ∗P < .05, ∗∗P < .01. Correlations between (E) FXIIa:C1INH, (F) FXIa:C1INH, and (G) PKa:C1INH with FIXa-AT were calculated and analyzed by linear regression. Mean r with range and P value is reported on graphs. AT, antithrombin.