Acute Interstitial Nephritis (Tubulointerstitial Nephritis)

Acute Interstitial Nephritis (AIN) is a condition that affects the kidneys, specifically the spaces between the tiny filtering units called tubules. It usually happens when the body's immune system reacts to certain medications, infections, or other triggers, causing inflammation in the kidney tissue. This inflammation can reduce the kidneys' ability to filter waste and balance fluids and electrolytes properly. People with AIN may experience symptoms like fever, rash, and changes in urine output, although sometimes it can be subtle. The condition mainly impacts the renal system and can lead to acute kidney injury if not recognized and managed promptly.

Acute Interstitial Nephritis (AIN) is an immune-mediated inflammatory disorder characterized by infiltration of the renal interstitium and tubules by inflammatory cells, predominantly lymphocytes, eosinophils, and monocytes. It is most commonly caused by a hypersensitivity reaction to drugs such as NSAIDs, antibiotics (e.g., beta-lactams), and proton pump inhibitors, but can also result from infections or systemic diseases. The inflammation leads to tubulointerstitial edema and impaired tubular function, causing acute kidney injury with decreased glomerular filtration rate. Clinically, AIN presents with nonspecific symptoms including fever, rash, and eosinophilia, and may be accompanied by sterile pyuria and hematuria. The condition is significant because it is a potentially reversible cause of acute renal failure if identified early and the offending agent is removed.