Renal Path: Tubulointerstitial Disease Flashcards
What are the two general mechanisms contributing to diseases of the tubules and interstitium? What form of disease do they each cause?
- ischemic/toxic injury to tubules = acute tubular necrosis
2. inflammatory reactions of the tubules and interstitium = tubulointerstitial nephritis
Acute tubular necrosis is the most common cause of what?
acute renal failure
Both ischemic and toxic acute tubular necrosis involve the formation of casts, but how do they differ in terms of the necrosis?
ischemic type has scattered necrosis throughout the nephron
toxic type has necrosis specifically in the proximal tubule (since that’s where the drugs will encounter the tubules first)
How can you get repair of acute tubular necrosis?
the necrosis that occurs doesn’t usually affect the basement membrane
the intact basement membrane is therefore able to secrete growth factor to help cells regenerate
Describe the pathogenesis of acute tubule necrosis.
- some form of endothelial injury occurs in the kidney
- the damaged cells will release cytokines which trigger a local inflammatory response
- intrarenal vasoconstriction actually occurs, decreaseing glomerular plasma flow and O2 deliver
- the dead cells slough off and obstruct the lumen
What are the pathways that lead to vasoconstriction in acute tubular necrosis?
the renin-angiotensin system
endothilin release by endothelial cells
decreased NO production
What will the pathology look like in acute tubular necrosis?
necrosis within the tubules
sloughing of the tubular cells
hyaline and granular casts
interstitial edema and incresaed lymphocytes
What additional microscopic finding might you see with toxic ATN?
ATN from ethylene glycol poisoning will have calcium oxalate crystals in the tubular lumens
What are the three stages of the ATN clinical course?
- initiation
- maintenance
- recovery
What happens initiation phase?
a slight decline in urine output and increased BUN, lasts for about 36 hours
What happens during the maintenance stage?
oliguria
salt and water overload with edema
increased BUN, hyperkalemia, metabolic acidosis
often requires dialysis
What happens during the recovery phase?
A steady increase in urine volume - actually a massive increase like 3 L/days
hypokalemia due to loss of K
What is the prognosis for nephrotoxic ATN? What about ATN related to shock/multiorgan failure?
nephrotoxic ATN has a 95% recovery rate if the patient survives the initial event
prognosis for ATN related to shock/organ failure is only 50% survival
What are the two main forms of tubulointerstitial nephritis? What characterizes each?
acute: with pMNs/Eos and edema
chronic: fibrosis and tubular atrophy
Clinically, what will tubulointerstitial nephritis present with?
polyuria
nocturia
metabolic acidosis
What is a common infectious cause of tubulointerstitial nephritis?
pyelonephritis
What is a common metabolic disease leading to TIN?
gout - urate buildup in the kidneys
What is a neoplasm common associated with TIN?
multiple myeloma
Acute pyelonephritis is a bacterial infection of the kidneys. What are some factors predisposing people to progress to chronic pyelonephritis?
structural issues - obstruction form BPH, tumor or stones
neurogenic bladder
vesiculoureteral reflux
What will the morphology be for acute pyelonephritis if you got a bopsy?
interstitial suppurative inflammation with PMNS
intratubular aggregates of neutrophils
tubular necrosis
How does an acute pyelonephritis heal microscopically
heals by scarring, with subsequent tubular atrophy and interstitial fibrosis with lymphocytes
If the issue is in part due to vesiculoureteral reflux, what parts of the kidney are most commonly affected?
the upper and lower poles (because thos eaer teh places where it’s most likely to reflux to)
What is a major complication of acute pyelonephritis that occurs mainly in diabetics of people with obstructions?
papillary necrosis
what does papillary necrosis look like?
gross: yellow necrosis at the papillary tips
micro: coagulative necrosis of th epapillary tips