Active proliferative glomerulonephritis (APGN)
Definition.
The term APGN encompasses a number of glomerular diseases which have in common an increased number of cells within the glomerular structures (mesangium and/or the capillary lumens and/or the Bowman’s space), with or without necrotizing lesions.

In mild forms, serum creatinine is normal and proteinuria may be either absent or light. In other cases, renal function deteriorates rapidly (over few days) while proteinuria is variable, from mild to severe (nephrotic range).

In the most severe cases, the distinguishing feature of the urinary sediment is the presence of a high number of dysmorphic erythrocytes (e.g., >50/HPF up to too many to count) associated with a variable amount of erythrocytic casts.
Other frequent particles are: leukocytes (~1-10/HPF), renal tubular epithelial cells (0->=1/HPF), and epithelial, leukocytic, granular, and/or waxy casts.

The most frequent types of APGN in the Renal Unit of the scientific editors are:
IgA nephropathy; mesangiocapillary GN; acute postinfectious GN; pauci-immune GN, Class III and IV lupus nephritis.