Tubulo-Interstitial Diseases Flashcards
What are the 2 broad groups of conditions?
- Acute tubular necrosis
- ischaemic or toxic necrosis of tubular cells
- Tubulointerstitial nephritis
- more commonly just “interstitial” nephritis
- inflammatory reactions involving the tubules and/or interstitium
What does acute tubular necrosis cause?
acute renal failure
What is acute tubular necrosis characterized by?
- characterized by acute destruction of tubular
epithelial cells - most commonly secondary to ischaemia, but
can also be due to direct toxic cell damage - potentially reversible, since tubular cells can
regenerate given time
Acute tubular necrosis due to ischemia is caused by?
- “shock” (rapid uncompensated fall in systemic BP)
e. g. in trauma, burns, falciparum malaria, pancreatitis, sepsis, DIC, blood transfusion reactions etc OR
2) reduction in intrarenal blood flow (RPGN, acute interstitial nephritis, urinary obstruction)
- remember, tubular blood flow is from post-glomerular capillary bed - and tubules are metabolically very active, thus susceptible to ischaemia
Which heavy metals cause cause ATN?
Pb, Au, As, Cr etc
Which organic solvents cause ATN?
CCl4, chloroform
Which drugs cause ATN?
antibiotics (espec gentamicin), anti-viral agents, NSAIDs, mercurial diuretics
Name toxins that cause ATN?
- iodinated contrast agents used for X rays
- pesticides
- glycols – ethylene glycol (“antifreeze”)
Describe the macro morphology of ATN?
Pale swollen edematous kidney, blurred cortico-medullary junction
Describe the micro anatomy of ATN?
- focal tubular epithelial necrosis and apoptosis
- basement membrane rupture
- interstitial edema
- epithelial regeneration
Distribution of tubular damage depends on?
cause
- ischaemic type - any part of nephron
- toxic type - only proximal tubules
Why does distribution of tubular damage depend on cause?
What are the effects of ATn?
- initial (~ 36 hrs) (usually missed) – slight increase in urine output and rise in serum urea
- oliguric – urine output 400 ml or less/day, so water, Na+ and K+ retention, rising urea, metabolic acidosis – danger of pulmonary oedema & cardiac dysrhythmias
- diuretic – urine output above normal, so loss of water, Na+ & K+ – danger of dehydration
What are the effects of ATn?
- initial (~ 36 hrs) (usually missed) – slight increase in urine output and rise in serum urea
- oliguric – urine output 400 ml or less/day, so water, Na+ and K+ retention, rising urea, metabolic acidosis – danger of pulmonary oedema & cardiac dysrhythmias
- diuretic – urine output above normal, so loss of water, Na+ & K+ – danger of dehydration
- complete recovery possible
Describe the pathogenesis of the 3 phases ATN?
initial – tubular cells begin to lose concentrating ability
oliguric – tubular epithelium lost, and so is reabsorption of most of glomerular filtrate
diuretic – regenerating epithelium does prevent much reabsorption, but can’t yet concentrate
- once concentrating ability restored, complete return to normal
What is renal cortical necrosis?
the destruction of cortical tissue resulting from renal arteriolar injury and leading to chronic kidney disease
What are the causes of renal cortical necrosis?
- A severe effect of shock on the kidneys than ATN produces
- also caused by rapid uncompensated fall in systemic BP (“shock”)
Describe the pathogenesis of renal cortical necrosis?
hypotension is so severe that renal blood flow is diverted into medullary vasa recta away from cortex
- whole cortex becomes infarcted
- irreversible
What is tubulointerstitial nephritis?
inflammation that affects the tubules of the kidneys and the tissues surrounding them (interstitial tissue)
- this disorder may be caused by diseases, drugs and toxins that damage the kidneys
Describe primary tubulointerstitial nephritis?
lacks significant glomerular or vascular injury
Describe secondary tubulointerstitial nephritis?
due to glomerular disease, systemic or vascular disorders
Describe acute tubulointerstitial nephritis?
interstitial edema, neutrophils, focal tubular necrosis
Describe chronic tubulointerstitial nephritis?
mononuclear inflammation, interstitial fibrosis, tubular atrophy
Describe symptoms of acute drug induced TIN?
- Onset 15 days after exposure (not dose related)
2. Rash, fever, eosinophilia, hematuria, mild proteinuria; 50% have rising creatinine or acute renal failure