Which urinalysis finding is most characteristic of glomerulonephritis?

• A. Dysmorphic red blood cells
• B. Hematuria with RBC casts
• C. Proteinuria with no blood
• D. Bacteria in urine

Answer: (B)

Glomerulonephritis causes bleeding from damaged glomeruli into the urinary space, and red blood cells that enter the tubules can form casts, giving a pattern of blood in the urine with red blood cell casts. This combination is highly characteristic of a nephritic process, since it reflects both glomerular injury and tubular downstream effects. While red blood cells can be dysmorphic in glomerular disease, the presence of red blood cell casts specifically points to glomerular bleeding with tubular involvement, making it the best indicator. Proteinuria without blood suggests nephrotic-range involvement but not the nephritic pattern, and bacteria in the urine implies infection rather than glomerulonephritis.