Factor XIII deficiency is a genetic bleeding disorder characterized by deficiency of clotting factor XIII resulting in prolonged, uncontrolled bleeding episodes. Unfortunately, the currently available, clinically-approved Factor XIII activity assays are technically challenging. Researchers at Nationwide Children’s Hospital have developed a new method for the determination of blood coagulation factor XIII enzymatic activity in a conventional enzyme-linked immunosorbent assay (ELISA). This method enables direct quantification of factor XIII as opposed to currently available indirect methods of measurement. This proof-of-principle technology provides improved, sensitive and simplified procedure for factor XIII estimation.