Which urinalysis finding is typical of glomerulonephritis?

Which urinalysis finding is typical of glomerulonephritis?

• A. WBC casts
• B. Dysmorphic red blood cells with RBC casts
• C. Proteinuria only
• D. Hyaline casts

Answer: (B)

Glomerulonephritis injures the glomerular filtration barrier, leading to leakage of blood into the urine. The most telling urinalysis pattern is hematuria with dysmorphic red blood cells and red blood cell casts, which point to a glomerular source of bleeding. Dysmorphic RBCs arise because red cells become irregular as they pass through damaged glomeruli and tubules, and RBC casts form when those cells are trapped in tubules with Tamm-Horsfall protein, creating casts that indicate a glomerular origin. Other findings fit different processes: WBC casts suggest tubulointerstitial inflammation or infection rather than glomerular bleeding; proteinuria alone can occur but isn’t specific to glomerulonephritis; hyaline casts are nonspecific and can appear in normal urine or mild kidney stress.

Glomerulonephritis injures the glomerular filtration barrier, leading to leakage of blood into the urine. The most telling urinalysis pattern is hematuria with dysmorphic red blood cells and red blood cell casts, which point to a glomerular source of bleeding. Dysmorphic RBCs arise because red cells become irregular as they pass through damaged glomeruli and tubules, and RBC casts form when those cells are trapped in tubules with Tamm-Horsfall protein, creating casts that indicate a glomerular origin. Other findings fit different processes: WBC casts suggest tubulointerstitial inflammation or infection rather than glomerular bleeding; proteinuria alone can occur but isn’t specific to glomerulonephritis; hyaline casts are nonspecific and can appear in normal urine or mild kidney stress.