The invention provides assay methods of detecting plasma protease C1 inhibitor (C1-INH) that binds plasma kallikrein, Factor XII, or both, and uses thereof for identifying subjects at risk for or suffering from a pKal-mediated or bradykinin-mediated disorder. Provided methods permit analysis of patients with plasma kallikrein-mediated angioedema (KMA), or other diseases mediated by pKal useful in the evaluation and treatment.