What finding in urine is characteristic of acute glomerulonephritis?

Acute glomerulonephritis is characterized by inflammation of the glomeruli and is often associated with a variety of findings in the urine. One of the hallmark features of this condition is the presence of red blood cell (RBC) casts. These casts are formed when red blood cells leak through glomerular capillary walls that have been damaged by inflammation. The RBC casts indicate that there is glomerular bleeding, which is a significant pathophysiological aspect of acute glomerulonephritis.

In addition to RBC casts, patients may also experience hematuria, proteinuria, and varying degrees of renal impairment. The presence of RBC casts in the urine is particularly indicative of glomerular injury, distinguishing acute glomerulonephritis from other renal pathologies.

The other findings mentioned in the options are relevant to different renal or urinary conditions. White blood cell (WBC) casts are typically associated with renal tubular interstitial inflammation, often seen in pyelonephritis. Calcium oxalate crystals are generally linked to metabolic derangements or stone disease rather than an inflammatory glomerular condition. Protein casts can indicate glomerular issues as well, but they are not specific to acute glomerulonephritis