In postinfectious glomerulonephritis, what is commonly observed in the microscopic examination of urine?

In postinfectious glomerulonephritis, the hallmark finding on microscopic examination of urine is the presence of dysmorphic red blood cells and red blood cell casts. This condition typically follows a streptococcal infection, which leads to inflammation and damage in the glomeruli, resulting in hematuria.

Dysmorphic red blood cells are indicative of glomerular bleeding, as they undergo changes in shape while passing through the affected glomeruli. The presence of RBC casts, formed when red blood cells clump together within the renal tubules, signifies that the bleeding is due to glomerular pathology rather than a lower urinary tract issue.

Other findings such as elevated protein levels may also be observed, but the key elements in identifying postinfectious glomerulonephritis in urine microscopy are the dysmorphic red blood cells and RBC casts, which reflect the underlying glomerular damage linked to the recent infection.