Association of a circulating factor XI anticoagulant and disseminated intravascular coagulation (DIC) is described in a 33-year-old woman. Although the patient had rheumatoid arthritis and a bacterial infection treated with antibiotics, the anticoagulant was thought to be secondary to systemic lupus erythematosus. Curiously, the low levels of factor XI did not prevent the DIC from developing.
(Arch Intern Med 1981;141:515-517)