 Serum analysis often aids in the diagnosis of a specific underlying disease.The presence of anti-glomerular basement membrane (GBM) antibodies suggests type I RPGN; antinuclear antibodies (ANA) may support a diagnosis of systemic lupus erythematosus and type II RPGN; and type III and idiopathic RPGN are frequently associated with anti-neutrophil cytoplasmic antibodies (ANCA)-positive serum.Impaired kidney function in an individual who has had the condition for fewer than three months is characteristic of RPGN.