Interstitial nephritides

Tubulointerstital nephritis

• Inflammation of the renal interstitium, it may be acute or chronic

Acute tubulointerstial nephritis

• Is mediated by an immune reaction to mediactions, infections and other causes
• Drugs;
  • NSAIDs
  • Antibiotics – cephalosporins, penicillins, sulphonamides, rifampicin
  • Diuretics – furosemide, thiazides
  • Also – allopurinal, cimetidine, amphotericin
• Infections
  • Staph, Strep, Brucella, Leptospira
• Immune disorders
  • SLE, GN
• May present with renal impairment, hypertension or acute renal failure
• Systemic features include fever, rash, arthralgia, eosinophilia, uvetitis, raised IgE
• Treatment
  • Stop cause
  • Prednisolone 1mg/kg
• Most have full recovery of renal function

Chronic tubulointerstital nephritis

• Results from many disorders leading to extensive fibrosis and tubular loss on renal biopsy
• Patients present with chronic renal failure
• Causes;
  • Chronic pyelonephritis
  • Sickle cell disease
  • Lead or cadmium intoxification

Analgesic nephropathy

• Associated with prolonged heavy ingestion of compound analgesics – NSAIDs, paracetamol
• Leads to interstitial nephritis and papillary necrosis
• Presents with sterile pyuria, UTI, symptoms of chronic renal failure or hypertension

Urate nephropathy

• Acute crystal nephropathy
  • Occurs when insoluble uric acid crystals deposit causing blockage of the tubules
  • Mainly caused by excessive uric acid caused by cell lysis during chemotherapy
  • Plasma urate is often raised and there is birefringent crystals on microscopy
  • Treatment
    • Good hydration
    • Allopurinal pre-chremotherapy
    • Urinary alkalinization with sodium biocarbonate (uric acid is more soluble in alkaline conditions)
• Chronic crystal nephropathy
  • Whether is it associated with gout is debatable but it is associated with Lesch-Nyhan syndrome
  • Treat with allopurinol