RENAL INX-RBC CASTS

SUMMARY

1. RBC casts or "dysmorphic" RBCs indicate probable glomerulonephritis/nephritic syndrome.

2. When there are few RBCs on microscopic analysis, but the urine dipstick is positive for blood, think of hemoglobinuria or myoglobinuria (rhabdomyolysis).

3. Determine if hematuria is due to intrinsic renal disease or genitourinary bleeding: hematuria assoc. with proteinuria, dysmorphic cells and/or RBC casts is always due to glomerular bleeding.

4. Isolated microscopic or gross hematuria is more likely to be urologic in origin. Complete GU imaging with renal U/S, MRI, or CT must be performed to exclude renal cell or other GU tract carcinomas.

Reference(s)

Wilkinson, I. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].