C3 and systemic lupus erythematosus: This patient had arthritis, nonscarring alopecia, autoimmune hemolytic anemia, leukopenia, thrombocytopenia, subacute cutaneous lupus, positive ANA and dsDNA, anticardiolipin antibodies, and low C3 and C4, which account for the diagnosis of SLE with a score of 33 initially, and later with a score of 43 with the development of lupus nephritis, according to the 2019 EULAR/ACR diagnostic criteria for SLE [3].