Step 1 First Aid Rapid Practice Test

Acute interstitial nephritis is an immune-driven inflammation of the kidney interstitium that often arises as a reaction to certain medications. The drugs most commonly linked to this condition are nonsteroidal anti-inflammatory drugs, penicillin-type antibiotics, and diuretics. After starting one of these agents, the immune system can mount a hypersensitivity response in the kidney that brings in inflammatory cells, especially eosinophils, leading to edema and impaired tubulointerstitial function. Clinical clues often include fever, rash, and sometimes eosinophilia or eosinophils seen in the urine, with a rise in creatinine indicating acute kidney injury. The primary step in management is stopping the offending drug, which frequently results in improvement. In more severe or persistent cases, corticosteroids may be used to hasten recovery. Other medications can affect the kidneys in other ways, but they are not classic culprits for acute interstitial nephritis, which is why this trio stands out as the typical offenders.