10779/rcsi.10781960.v1 Helen Fogarty Helen Fogarty Mary Byrne Mary Byrne Niamh M. O'Connell Niamh M. O'Connell Kevin Ryan Kevin Ryan Barry White Barry White James S. O'Donnell James S. O'Donnell Michelle Lavin Michelle Lavin Acquired factor xiii deficiency: An uncommon but easily missed cause of severe bleeding. Royal College of Surgeons in Ireland 2019 Acquired Factor Xiii Deficiency Bleeding. Clinical Pharmacology and Therapeutics 2019-11-22 16:17:06 Journal contribution https://repository.rcsi.com/articles/journal_contribution/Acquired_factor_xiii_deficiency_An_uncommon_but_easily_missed_cause_of_severe_bleeding_/10781960 <p>Factor XIII (FXIII) is a plasma clotting protein involved in clot stabilization. Severe FXIII deficiency may present with severe, even fatal bleeding. Critically however, routine coagulation assays may be normal and only specific FXIII assays will detect the abnormality. Herein we discuss a case report of a patient with acquired FXIII deficiency in order to highlight the clinical challenges associated with establishing the diagnosis and discuss the treatment approach. A 70-year-old man presented with a gluteal haematoma despite no preceding personal history of bleeding. Extensive initial haemostatic investigations were normal until a specific FXIII assay showed a marked reduction in FXIII levels. With directed treatment, bleeding episodes ceased and remission was achieved. Clinical awareness of FXIII deficiency is important, so appropriate testing can be implemented in patients with unexplained bleeding diatheses, particularly those in whom bleeding responds poorly to standard replacement therapy.</p>