Secondary causes of nephrotic syndrome include (1) autoimmune and vasculitic diseases, such as Henoch-Schönlein purpura (HSP), systemic lupus erythematosus, and antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis; (2) infectious diseases, such as congenital syphilis, malaria, human immunodeficiency virus (HIV), and hepatitis B and C; (3) malignancy; (4) environmental and drug exposure, such as heroin and mercury; and (5) systemic diseases such as diabetes mellitus, among many other causes (see Etiology).