Which urinary finding is typically associated with allergic interstitial nephritis?

Allergic interstitial nephritis is characterized by an inflammatory response in the interstitium of the kidney, often triggered by medications, infections, or autoimmune diseases. One of the hallmark urinary findings in this condition is the presence of white blood cell casts.

White blood cell casts are formed when white blood cells accumulate within the renal tubules and are excreted in the urine. Their presence indicates an inflammatory process occurring within the kidney, typically associated with conditions like interstitial nephritis. In this case, allergic interstitial nephritis stimulates an immune response that leads to infiltration of white blood cells, primarily eosinophils, into the renal interstitium, which is why their casts can be found in the urine.

Other findings in allergic interstitial nephritis might include elevated levels of eosinophils in the blood and urine, but the presence of white blood cell casts is specifically indicative of this type of renal inflammation. While red blood cell casts are typically associated with glomerular disease, waxy casts may indicate chronic kidney disease, and Maltese crosses relate to conditions causing lipiduria, none of these findings reflect the pathophysiological changes seen in allergic interstitial nephritis. Thus, white blood cell casts are the correct and most relevant