Efficiency of intermittent prophylactic factor XIII subsitution in factor XIII a subunit deficiency.

Four patients with congenital factor XIII (FXIII) a subunit deficiency were treated with prophylatic FXIII substitution at a dose of 1, 000 or 1, 250 units every four weeks for 3 to 12 years to avoid the recurrence of severe bleeding, especially intracranial bleeding, which all had experienced. We evaluated the efficacy of this prophylactic therapy on the basis of both the clinical manifestation of hemostasis and of in vitro analysis of fibrin crosslinking in patient's plasma. Although the FXIII dosage was increased from 7, 837±4, 593units/yr to 12, 699±1, 336units/yr after the start of prophylaxis, the number of bleeding episodes were remarkably decreased from 4.15±1.54/yr to 0.23±0.19/yr with no life-threatening hemorrhage. Both γ-dimer and α-polymer formation was shown in fibrin obtained from patient's plasma taken 30 minutes after the administration of 1, 000units of FXIII, and γ-dimer crosslinking was still observed in fibrin from the plasma taken four weeks after the administration. These data suggest that intermittent prophylactic FXIII administration is valuable in the treatment of patients with congenital FXIII a subunit deficiency.