<prompt> In which of the following the serum C3 not persistently low?Poststreptococcal glomerulonepheritisMembranoproliferative glomerulonephritisLupus nephritisGlomerulonephritjis related to bacterial endocarditis  <response>: SerumC3 levels are persistently low in membranoproliferative GN, lupus nephritis, and glomerulonephritis related to infective endocarditis. Poststreptoccal glomerulonephritis: SerumC3 Levelsaredepressed within2weeksinalmost90ofcases.However,C3 levelsreturntonormal within6to 8weeks. Persistentlydepressedlevelsaftehisperiodshouldsuggestanothercausesuchas C3 nephriticfactor membranoprolif-erativeglomerulonephritis 