Introduction: Acquired factor XIII (FXIII) deficiency is a rare and often underdiagnosed bleeding disorder. Because standard coagulation tests typically yield normal results, diagnosis and treatment are often delayed in patients with unexplained hemorrhage. Case Presentation: We report the case of a 56-year-old man who presented with severe, recurrent epistaxis unresponsive to conventional management. Initial coagulation tests—including prothrombin time, international normalized ratio, activated partial thromboplastin time, and fibrinogen levels—were all within normal limits. Despite interventional radiology and surgical measures, bleeding persisted. An FXIII activity assay revealed a mild deficiency (48.7%; reference range: 60–130%). Administration of recombinant FXIII (catridecacog, 10 IU/kg) led to rapid clinical improvement and resolution of bleeding. Discussion: This case illustrates the diagnostic challenge posed by acquired FXIII deficiency and underscores the importance of including it in the differential diagnosis of unexplained bleeding, especially when standard coagulation parameters are unremarkable. Conclusion: Prompt recognition and targeted replacement therapy with recombinant FXIII can be life-saving in acquired FXIII deficiency. FXIII activity testing should be considered early in patients with persistent bleeding of unknown origin.
Romanelli et al. (Wed,) studied this question.