Normal complement levels of c3 and c4 cannot completely exclude lupus erythematosus, and it is recommended that the patient should consult a doctor in time, and it is necessary to combine the clinical manifestations with the results of relevant examinations to make a judgment after a comprehensive analysis. 1. Clinical manifestations: As lupus erythematosus is a recurrent autoimmune disease, the complement level will gradually return to normal as the condition of lupus erythematosus is under control. The main manifestations of lupus erythematosus include alopecia, weight loss, erythema pteronyssinus, pallor of skin and mucous membranes, photosensitivity, joint pain, anemia, and the disease status needs to be judged in combination with the symptoms. 2. Relevant examination: normal complement c3 and c4 cannot completely exclude lupus erythematosus, and it is recommended to combine with some relevant examinations for diagnosis, such as doctor’s physical examination, preliminary judgment by observation and palpation; laboratory examination, such as liver and renal function, blood routine, autoantibodies, urine routine examination to determine whether there are abnormalities and so on to make a comprehensive judgment. If the above symptoms occur, it is recommended that patients go to the hospital in time to avoid delays.