Factor XII does play an important role in clot formation during in vitro measurements of the partial thromboplastin time, which causes these measurements to be markedly prolonged in patients with factor XII deficiency, usually well beyond even what is seen in hemophilia A, hemophilia B, or factor XI deficiency.
O factor XII xoga un importante papel na formación de coágulos durante as medidas in vitro do tempo de tromboplastina parcial activado, que causa que estas medidas dean resultados marcadamente máis prolongados en pacientes con deficiencia en factor XII, xeralmente con valores moito maiores incluso que os observados na hemofilia A, hemofilia B ou deficiencia de factor XI.