Plasma levels of prekallikrein, alpha-2-macroglobulin and C1-esterase inhibitor in patients with urticarial reaction to contrast media.

The plasma levels of prekallikrein, alpha-2-macroglobulin and C1-esterase inhibitor (C1 INH) in patients with previous urticarial reaction to contrast media (CM) were compared to those of a group of nonreacting age- and sex-matched controls. This study evaluated the value of these laboratory variables in predicting acute and delayed urticarial-type reactions.The study comprised 44 patients (reactors) with acute (n = 29) or delayed (n = 15) urticaria after administration of CM, and a group of age- and sex-matched controls.In the reactors, the levels of prekallikrein and alpha-2-macroglobulin were higher (p < 0.0001) and the level of C1 INH lower (p < 0.0001) than those of the controls. The level of prekallikrein decreased with increasing age (p = 0.02) and women had higher values than men (p = 0.0054). The level of alpha-2-macroglobulin was age-dependent (p = 0.006).Although high plasma prekallikrein activity, high plasma alpha-2-macroglobulin activity, and low plasma C1 INH activity are associated with urticaria-type reaction to CM, their value in predicting urticarial reaction is limited because prekallikrein is age- and sex-dependent, and alpha-2-macroglobulin is age-dependent.