What happens in acute disease to the interstitium?
The interstitium will swell
What is the difference in cell structure between the distal and proximal tubule?
Microvilli
What is the most common type of kidney disease?
Tubulointerstitial diseases
What are the most important causes of tubulointersititial injury
Ischemic
Infection
Acute or Chronic Tubulointerstitial Nephritis
What usually causes Acute tubular necrosis?
Almost always due to ischaemia
What happens to dead cells in the tubules?
Epithelial cells degenerate and detach from tubular basement membrane (slough off)
What is the result of acute tubular necrosis?
Without functioning epithelium the tubule can no longer fulfil its functions: the glomerular filtration rate falls, electrolyte balance fails, urea and creatinine accumulate in blood etc.
Is ATN reversible?
ATN is a reversible lesion; if the patient is supported (which may mean dialysis) regeneration and complete recovery occur but may take weeks
What is associated with recovery from ATN?
Recovery is often associated with diuresis (increased production of urine)
What are some causes of delayed function after renal transplant?
– Problems due to the transplantation procedure (particularly ischaemia)
– Early rejection (can happen very early)
– Drug toxicity (many immunosuppressive drugs unfortunately potent nephrotoxins !)
– Recurrent primary disease (though it would be very early !)
What is the distinction between hypoperfusion and ischemic ATN?
Hypoperfusion is ischemia for a short time, ATN is the same process over an extended period which causes necrosis of tubular epithelium – it’s no longer just a lack of raw material, it’s damage to the machinery (which now needs repair before it can work again).
Seen with toxins that affect tubular epithelium?
– Heavy metals (esp. mercury)
– Some antibiotics
– Some cancer chemotherapy drug
How does Acute interstitial nephritis present?
Usually presents as acute renal failure, sometimes with some blood or protein in urine
Lymphocytes are seen under the microscope
How do drugs cause ATN?
Very often due to drug allergy (e.g. antibiotics)
What is Pyelon?phritis
Bacterial infection that affects the kidney
What part of the nephron are usually infected by bacteria?
Everything except glomerulus
What type of infection is pyelonephritis?
Almost always gram negative
Ascending infection
What are the symptoms of pyelonephritis?
– Acute onset
– Fever, chills, lumbar tenderness and pain
– Discomfort when urinating (and frequency)
Is kidney function maintained in Pyelonephritis?
Renal function usually preserved. Hypertension not a component
Most common gram negative causes of Pyelonephritis?
– E. coli
– Klebsiella sp.
– Proteus sp.
– Pseudomonas sp
What causes Chronic Pyelonephritis?
Generally obstruction
What occurs as the result of Chronic Pyelonephritis?
Results in interstitial scarring, tubular atrophy, depressed ‘saddle shaped’ scars visible on the renal surface
What is reflux nephropathy?
Renal damage due to backflow (NOT obstruction) of urine from the lower tract
what is Analgesic nephropathy?
A chronic, progressive tubulo-interstitial disease induced by the prolonged use of particular analgesics
