Eosinophiluria is most characteristic of which condition?

• A. Postinfectious glomerulonephritis
• B. Atheroembolic disease
• C. Septic emboli
• D. Acute interstitial nephritis

Answer: (D)

Eosinophiluria points to an allergic-type injury of the kidney interstitium, which is most characteristic of acute interstitial nephritis. This condition is typically drug-induced and involves hypersensitivity reactions that bring eosinophils into the interstitial tissue and, with Hansel staining, into the urine. Clinically you often see a recent drug exposure with fever, sometimes rash, and renal impairment; urine analysis may show sterile pyuria with eosinophils and white blood cell casts. While other renal conditions can cause inflammation or embolic phenomena, eosinophils in the urine are a classic, relatively specific clue for drug-related interstitial nephritis, making it the best answer.