Which finding would support glomerular rather than extraglomerular hematuria?

Which finding would support glomerular rather than extraglomerular hematuria?

• A. Presence of RBC casts
• B. RBC morphology normal
• C. No proteinuria
• D. Hematuria absent

Answer: (A)

The key idea is that certain urine sediment findings point to where the bleeding originates. RBC casts form when red blood cells pass through damaged glomeruli, enter the tubules, and become incorporated into tubular casts. This requires a glomerular source and tubular processing, so finding RBC casts strongly indicates glomerular bleeding. RBC morphology is often dysmorphic with glomerular bleeding, but normal morphology would be less supportive of a glomerular origin. No proteinuria would argue against a glomerular process, since glomerular injury often accompanies protein leakage. Hematuria absent obviously means there’s no visible blood in the urine. Among these options, the presence of RBC casts most specifically points to a glomerular source.

The key idea is that certain urine sediment findings point to where the bleeding originates. RBC casts form when red blood cells pass through damaged glomeruli, enter the tubules, and become incorporated into tubular casts. This requires a glomerular source and tubular processing, so finding RBC casts strongly indicates glomerular bleeding.

RBC morphology is often dysmorphic with glomerular bleeding, but normal morphology would be less supportive of a glomerular origin. No proteinuria would argue against a glomerular process, since glomerular injury often accompanies protein leakage. Hematuria absent obviously means there’s no visible blood in the urine. Among these options, the presence of RBC casts most specifically points to a glomerular source.