Commonly ordered labs to rule out glomerulonephritis or vasculitis:
Glomerulonephritis: C3, C4, anti-ASO, ASK, HIV, HBsAg, HCV, RPR, blood cultures; if there is rash or arthritis: ANA, ANCA, cryoglobulin, SPEP, UPEP
Vasculitis: C3, C4, ANA, ANCA; HBsAg, HCV, cryoglobulins, ESR, RF, SS-A, SS-B, HIV
(SS-A = anti-Ro antibody; SS-B = anti-La antibody)