ITE Nephrology Practice Test

White blood cell casts reflect inflammation within the renal tubules and interstitium, not the glomeruli. They form when leukocytes infiltrate the tubular lumen and get incorporated into the cast matrix, signaling a tubulointerstitial process. That pattern fits acute interstitial nephritis, often drug-induced, and pyelonephritis, where infection or inflammation affects the renal interstitium and tubules. In nephrotic syndrome, the problem is primarily glomerular permeability, so you’d expect lipiduria and different casts rather than WBC-dominated ones. In glomerulonephritis, red blood cell casts are more characteristic due to glomerular bleeding. Thus, white blood cell casts point to tubulointerstitial inflammation, as seen in acute interstitial nephritis or pyelonephritis.