Friday, 12 November 2010

MRCP revision battle 47.3: Acute Interstitial Nephritis

Interstitial nephritis is inflammation of the renal interstitium.

Acute interstitial nephritis

This is an immune reaction to drugs or infection.
It accounts for 2% of all acute renal failure but 25% of drug-induced renal failure.

Features include:
  • acute renal failure
  • hypertension
  • systemic symptoms
    • rash
    • fever
    • eosinophilia, raised IgE

>1% urinary eosinophils suggests diagnosis

Renal biopsy would show infiltration of the renal interstitium with:
  • T lymphocytes
  • macrophages
  • plasma cells

Causes include:
  • infections: hanta virus, leptospirosis, mycobacterium, staph, strep
  • drugs: methicillin, NSAIDs, rifampacin, allopurinol, penicillin, cephalosporins, furosemide, thiazides, amphotericin, aspirin
  • sarcoid

Lets move on to consider a hat-trick of causes of chronic interstitial nephritis