TOPIC 10: chronic interstitial nephritis

Question 1

What is chronic interstitial nephritis?

Answer 1

• encompasses a variety of disorders that share histological appearances in kidney biopsy:
  1. extensive fibrosis
  2. lymphocytic infiltrate in scarred areas
  3. dilated and atrophic tubules
  4. glomeruli spared
• exists as a distinct DIAGNOSIS
• drug induced AIN of any cause may progress if not treated
• can also be a feature of progressive CKD of any cause including GRN

Question 2

Causes of CIN

Answer 2

1. Drugs
2. autoimmune
3. chronic infection
   - -> like AIN
4. metabolic causes (chronic hypokalemia due to anorexia)
5. heavy metals

6.reflux nephropathy
7. urate nephropathy (TLS, Gout)
8 radiation nephropathy
–> RUR nephropathy

Question 3

Clinical features of CIN

Answer 3

Slowly progressing renal failure with insidious onset and usually mild symptoms:

1. nocturia, polyuria
2. tubular proteinuria (<1g/day)
3. urinary sediment (leukocytes, RBC casts)
4. glucosuria (Fanconi) & RTA
5. renal anemia
6. osteomalacia
7. normal BP
8. Small, symmetrical kidneys on US ( except reflux nephropathy where they’re not symmetrical)

Question 4

Management of CIN

Answer 4

-eliminate the inciting agent!