Which finding is most characteristic of acute glomerulonephritis on urinalysis?

• A. Red blood cell casts
• B. White blood cell casts
• C. Glucosuria
• D. Protein crystal formation

Answer: (A)

The key concept is that glomerular inflammation allows red blood cells to leak into the filtrate, and as they flow through tubules they become trapped in a protein matrix to form red blood cell casts. This combination—hematuria with RBC casts in the urine—is the most characteristic sign of acute glomerulonephritis on urinalysis because it directly reflects a glomerular source of bleeding.

White blood cell casts point more toward tubulointerstitial inflammation or infection rather than primary glomerular bleeding. Glucosuria implies proximal tubule dysfunction or diabetes mellitus, not a glomerular lesion. Protein crystals are not a typical feature of acute glomerulonephritis; while some proteinuria can occur, the hallmark finding is the presence of RBC casts.