Overview of Membranous Nephropathy VIDEO Etiology of Membranous Nephropathy Membranous nephropathy is usually idiopathic, but it may be secondary to any of the following: Medications (eg, gold therapy, penicillamine, nonsteroidal anti-inflammatory drugs [NSAIDs]) Infections (eg, hepatitis B or C virus infection, syphilis, HIV infection) Autoimmune disorders (eg, systemic lupus erythematosus [SLE]) Thyroiditis Cancer Parasitic diseases (eg, malaria, schistosomiasis, leishmaniasis) Depending on the patient's age, 4 to 20% have an underlying cancer, including solid cancers of the lung, colon, stomach, breast, or kidney; Hodgkin or non-Hodgkin lymphoma; chronic lymphocytic leukemia; and melanoma.