Tubulo-interstitial Diseases

Question 1

Which is more common, glomerular disease or tubulo-interstitial disease?

Answer 1

tubulo-interstitial disease

Question 2

What is the interstitium?

Answer 2

a matrix of loose connective tissue (collagen) around the tubules - function is inseparable from the tubules

Question 3

What happens to the interstitium in chronic renal disease?

Answer 3

becomes enlarged and fibrous

Question 4

What are the most important tubulointerstitial injuries?

Answer 4

acute tubular necrosis, acute pyelonephritis, acute or chronic tubulointerstitial nephritis

Question 5

Why are the tubules susceptible to ischaemia and necrosis?

Answer 5

because the cells are very metabolically demanding and in cases of low blood volume will be relatively under perfused compared to places like the brain

Question 6

What is the commonest cause of acute renal failure?

Answer 6

acute tubular necrosis

Question 7

What happens in acute tubular necrosis?

Answer 7

hypo perfusion causes tubule cell necrosis and the tubule cells will die and detach and block up the lumen leaving a naked basement membrane - the tubule is no longer functioning

Question 8

Is acute tubular necrosis reversible?

Answer 8

yes - cells will regenerate and reline the tubules - but the patient may need dialysis to recover

Question 9

What often happens during recovery from ATN?

Answer 9

diuresis

Question 10

What happens to GFR in ATN?

Answer 10

it drops - so there is an increase in serum creatinine

Question 11

What are the possible reasons for kidney rejection?

Answer 11

problems during transplant (ischaemia), early rejection, drug toxicity (immunosuprresive drugs), recurrent primary disease

Question 12

What is toxic acute tubular necrosis?

Answer 12

Toxins that affect the tubular epithelium (heavy metals, antibiotics, chemotherapy) disturb mitochondrial function and lead to necrosis - see similar result as in ischaemia causing ATN

Question 13

What is acute interstitial nephritis?

Answer 13

where the interstitium and tubules are infiltrated with inflammatory cells (lymphocytes and often eosinophils) - often due to drug allergy - presents as acute renal failure, sometimes with blood or protein in the urine, sometimes with fever or rash

Question 14

What is the differential diagnosis for post streptococcal glomerular nephritis?

Answer 14

acute interstitial nephritis

Question 15

What is pyelonephritis?

Answer 15

a bacterial infection of the kidney that affects the parenchyma, calyces and renal pelvis

Question 16

How does pyelonephritis most commonly occur?

Answer 16

ascending infection from the bladder

Question 17

What organisms cause pyelonephritis?

Answer 17

usually gram negative organisms: E. coli, klebsiella, proteus, pseudomonas

Question 18

Does pyelonephritis usually affect renal function?

Answer 18

no

Question 19

What do you see macroscopically in pyelonephritis?

Answer 19

white streaks through the medulla (pus filled tubules)

Question 20

What are the symptoms of acute pyelonephritis?

Answer 20

fever, chills, lumbar tenderenss and pain, discomfort and frequency urinating

Question 21

What is chronic pyelonephritis often due to?

Answer 21

recurrent lower grade infections

Question 22

What is the result of chronic pyelonephritis?

Answer 22

interstitial scarring, tubular atrophy, saddle shaped scars on renal surface

Question 23

What is reflux nephropathy?

Answer 23

renal damage due to vesico-ureteric reflux

Question 24

What is analgesic nephropathy?

Answer 24

chronic, progressive tubulo-interstitial disease from the prolonged use of certain analgesics

Question 25

What is the result of chronic renal failure?

Answer 25

insuffiecient glomerular filtration to elimnate metabolic waste or maintain sodium and water homeostasis

Question 26

What are the most common causes of chronic renal failure?

Answer 26

diabetic nephropathy, glomerulonephritis, hypertension

Question 27

How does chronic renal failure cause hypertension?

Answer 27

activates RAAS

Question 28

At what stage of chronic renal failure do you see symptoms?

Answer 28

when down to 10% of kidney function