F8 and systemic lupus erythematosus: On 13th August, the quantitative detection of FVIII activity was detected, the test result was 2% (normal 50%–150%), the activity of coagulation factor XI was normal, and the FVIII inhibitor level was 8.5 Bethesda units (BU)/mL, leading us to speculate that the patient was suffering from SLE merged with AHA.