The half life of factor XIII in the management of inherited deficiency.

Following the injection of a large dose of factor XIII concentrate the in vivo half life of factor XIII was estimated in a patient with inherited deficiency. Factor XIII activity and enzyme concentration were measured quantitatively, and a qualitative assessment of the crosslinking of fibrin was also made for upto 6 weeks after the injection. The half life was found to be about 9--10 days. This is longer than most previous reports suggest. An explantation for this finding is offered. The relevance of the long half life of factor XIII to the prophylactic treatment of patients with inherited deficiency is demonstrated.