C4A and acute kidney injury: The Coombs test was negative. In addition, she was also found to have acute kidney injury (AKI) and liver impairment. The prothrombin time was increased (22.2 seconds), while the activated partial thromboplastin time and plasma fibrinogen level were normal. The viral hepatitis markers and autoimmune markers were all negative. The serum complement levels (C3 and C4) were normal. The C-reactive protein was 66 mg/L.