<prompt> In a case of glomerulonephritis GN , C3 is normal in all the following except?Diffuse lupus nephritisGood pasteurs syndromeIgA nephropathyHSP  <response>: Low C3 nephritis is observed in: Post-infectious GN, MPGNMembranoproliferative GN SLE Subacute bacterial endocarditis Cryoglobulinemia, shunt nephritis 