<prompt> The prognosis of rapidly proliferating glomerulonephritis Crecentric GN depands upon -Number of crescentsSize of crescentsshape of crescentsCellularity of crescents  <response>: Rapidly progressive glomerulonephritis RPGN is characterised by number of crescentsby rapid loss of renal function over days to weeks, usually in association with hypeension and oedema. Non-visible haematuria is almost always present with variable amounts of proteinuria, while characteristic red cell casts and dysmorphic red cells may be observed on urine microscopy . Renal biopsy typically shows crescentic lesions , often associated with necrotising lesions within the glomerulus , paicularly in small-vessel vasculitides. This pattern of presentation is typical of post-infectious glomerulonephritis, anti-GBM disease and small-vessel vasculitides p. 1040. It can also be observed in SLE and occasionally in IgA and other nephropathies . Causes of glomerulonephritis associated with low serum complement Post-infectious glomerulonephritis Subacute bacterial infection, especially endocarditis Systemic lupus erythematosus Cryoglobulinaemia Mesangiocapillary glomerulonephritis, usually complement type Ref Harrison20th edition pg 267 