A patient with acute renal failure proves a urine specimen that demonstrates normal osmolality and sodium content. The urine contains no casts, but RBCs are present. Which of the following is the most likely etiology of this patient’s acute renal failure?
- prerenal cause
- intrarenal — glomerulonephritis
- intrarenal — acute tubular necrosis
- intrarenal — interstitial nephritis
- postrenal cause
Answer: E
Postrenal cause
In pre-renal acute renal failure, the sodium content of the urine would be decreased (because the patient is volume depleted, so the kidneys try to retain Na – less is in the urine) In intrarenal disease, the urine would contain casts. So, this is a postrenal disease (usually a big prostate or stones) which would cause normal urine with rbc’s.
Know Your Content Blueprint
Acute renal failure is covered as part of the PANCE Genitourinary Blueprint
Review Topic: Acute renal failure (ReelDx)