Urinary - pathology Flashcards by Mary Tilling

What are the main functions of the kidney?

Formation of urine
Acid-base, water and electrolyte homeostasis
Endocrine - renin-angiotensin-aldosterone, vitamin D

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What are the 4 main structural components of the kidney?

Blood vessels
Glomerulus
Tubules
Interstitium

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What proportion of the cardiac output goes to the kidneys?

25%

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What are the arteries that make up the kidney?

Renal artery
Interlobar arteries
Interlobular arteries
Arcuate arteries

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Where are the arcuate arteries located in the kidney?

At the corticomedullary junction - between the cortex and the medulla

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What are the names of the vessels going to and from the glomerulus?

Afferent and efferent glomerular arterioles

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What makes up the three layers of the glomerular filtration barrier?

Fenestrated capillary epithelium
Glomerular basement membrane
Podocytes

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If injury occurs to the glomerular filtration barrier what is likely to start to appear in the urine?

Proteins - proteinuria

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What can disrupt tubular function in the kidneys?

Disruption of the close apposition of the tubules and peritubular capillaries

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What 4 things can enter the interstitium of the kidneys during disease processes?

Fluid
Cells
Connective tissue - collagen (fibrosis)
Other - calcium, amyloid

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What are some potential causes of renal vascular injury?

Embolism
Vascular injury/vasculitis
Loss of autoregulation of renal perfusion - ischaemic injury
Compression of blood vessels

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What does renal thromboembolism look like in the kidney?

Dark red area - less old infarction, acute
Regions of pallor - long time ischaemic
Wedge shaped

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What is the most common place for thrombi to cause infarction in the kidney?

Interlobular vessels - small end arteries
Cause localised infarction of a segment of the cortex

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What is the second most common place for thrombi to cause infarction in the kidney?

Arcuate or interlobar artery
Causes localised infarction of a segment of the cortex AND medulla

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What is the most uncommon place for thrombi to cause infarction in the kidney?

Renal artery
Causes total infarction of the kidney or of one half of the kidney

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Where are renal thromboemboli most likely to come from?

The heart - left side
e.g from hypertrophic cardiomyopathy or endocarditis

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What viruses can cause vascular injury/vasculitis causing kidney damage?

Canine herpesvirus - 2-3 week puppy
African/classical swine fever
Feline infectious peritonitis

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What controls perfusion of the kidney by vasodilating afferent arterioles in response to ischaemia to maintain perfusion?

Prostaglandin

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What drug can inhibit prostaglandins causing disturbed perfusion and ischaemia in the kidney?

NSAIDs

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What are some potential causes of compression of the renal vasculature and medullary necrosis?

Urinary obstruction
Pyelonephritis
Medullary amyloidosis

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What does glomerulosclerosis look like?

Fibrosis and thickening of the bowmans capsule
Abnormal glomerulus

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How does chronic kidney disease tend to change the gross appearance of the kidneys?

Granular appearance
Swollen with loss of cortical striation

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What is the difference between glomerulonephritis and glomerulopathy?

Glomerulonephritis - glomerular disease with secondary changes to the nephron components
Glomerulopathy - glomerular disease without inflammation

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What is the main cause of glomerulonephritis?

Glomerular deposition of immune complexes
Causing podocytes to lose foot processes and basement membrane to thicken, increasing permeability

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What are the different classifications of glomerulonephritis?

Membranous - changes primarily to the basement membrane Proliferative - cell components proliferate without changing the basement membrane Membranoproliferative - both

What are the consequences of glomerulonephritis?

Proteinuria Interstitial fibrosis Reduced nephron function

What does glomerular amyloidosis look like on histology?

Pink blobs of amyloid protein inside the glomerulus

What causes glomerular amyloidosis?

Chronic inflammatory diseases Neoplastic diseases

What is suppurative glomerulitis?

Bacteraemia - bacteria lodging in glomerular capillaries and interstitial capillaries forming microabscesses

What does suppurative glomerulitis look like on histology?

Mass of speckled purple in the glomerulus Small white foci on cortical surface surrounded by pink hyperaemic area

What are the 3 causes of tubular damage in the kidneys?

Nephrotoxins Ischaemia Infectious agents

What are some examples of nephrotoxins?

Drugs - NSAIDs, tetracyclins, aminoglycosides, cisplatin Antifreeze Raisins - dogs Lillies - cats Haemo/myoglobin

What are 4 tubular epithelial cell responses to tubular injury?

Atrophy Degeneration Necrosis Regeneration

What does acute tubular degeneration and necrosis look like on histology?

Very eosinophilic - pink Loss of nuclear detail Very swollen

What is a functional consequence of tubular injury?

Acute decrease in glomerular filtration rate and renal function causing oliguria/anuria - little to no urine production

How does myoglobin and haemoglobin affect the kidneys? What does it look like?

Haemoglobin - from haemolysis Myoglobin - from muscle injury They are nephrotoxins, can stain kidneys dark red-black to blue-black

What affects regeneration of tubular epithelial cells?

Whether the basement membrane is damaged or not If not damaged then tubular regeneration of epithelial cells can occur If damaged then fibrosis and tubular atrophy occurs

What is the word for disruption of the tubular basement membrane?

Tubulorrhexis

What occurs during epithelial regeneration following degeneration and necrosis of tubular epithelial cells?

Polyuria - limited reabsorption capacity

What does metabolism of ethylene glycol (antifreeze) produce?

Nephrotoxic metabolites and oxalate produced from breaking it down in the liver

What does oxalate cause in the kidney from metabolism of ethylene glycol (antifreeze)?

Tubular obstruction

What causes interstitial injury in the kidney?

Secondary to injury of other renal components Infectious agents Toxins

What are some interstitial responses to injury? When do you find them

Oedema Inflammation - acute (neutrophils) or chronic (lymphocytes, macrophages) Fibrosis - chronic kidney disease

What is pyelonephritis?

Inflammation of the renal pelvis and the renal tubules/parenchyma (tubulointerstitial nephritis) simultaneously

What causes pyelonephritis?

Ascending bacteria from a lower UTI

What are some predisposing factors for pyelonephritis?

Increased pressure in bladder or ureter - reflux of urine

What does pyelonephritis look like on gross histology?

Renal crest necrosis, hyperaemia Dilation of renal pelvis Cortical atrophy

What are simple renal cysts?

Grossly visible thin walled fluid filled cavities in the kidney parenchyma

What can cause simple renal cysts?

Congenital/aquired obstructive lesions of the nephrons Tubular basement membrane abnormalities Disorders of tubule epithelial cell growth

What is polycystic kidney disease?

Multiple renal cysts bilaterally on kidneys which grow over time and can cause renal failure

What does polycystic kidney disease look like?

Purple foci with semitransparent capsular surface

What causes polycystic kidney disease? What are predisposed?

Heritable condition in some breeds eg. bull terrier, persian cat Can be sporadic

What are juvenile nephropathies? What do they affect?

Variety of familial/hereditary conditions Cause chronic progressive renal disease in young dogs (between 4-18 months)

What are ectopic ureters?

When ureters dont empty into trigone of the bladder but instead into another area of the bladder eg. neck, urethra, repro tract

What do ectopic ureters predispose to?

Urinary incontinance - steady dribble of urine Ascending infections Obstructive disease

What is a retrocaval/circumcaval ureter?

Ureter has an abnormal spiral course around the caudal vena cava that occurs during development

What is a consequence of retrocaval/circumcaval ureter?

Mostly asymptomatic but is predisposed to obstruction

What is cystitis?

Urinary bladder inflammation

What are predisposing factors for cystitis?

Female Local infections Obstructive urinary diseases Diabetes mellitus - glucose in urine

What can cystitis be in cats?

Sterile - feline interstitial cystitis From stress causing neurogenic inflammation of the bladder wall

What are two different types/appearances of chronic cystitis?

Polypoid cystitis - fibrous tissue and chronic inflammatory cells Follicular cystitis - nodular proliferation of lymphoid tissue, grey white nodules surrounded by red hyperaemic zone

What is follicular cystitis often seen alongside?

Urolithiasis

What are more common - metastatic kidney tumours, or primary kidney tumours?

Metastatic are more common Twice as common as primary in dogs 7 times more common than primary in cats

What is the most common type of primary renal neoplasia?

Epithelial - carcinoma

What is a type of embryonal primary tumour found in the kidney?

Nephroblastoma - from residual embryonal cells that would normally differentiate into nephrons

What are the consequences of a nephroblastoma?

Mostly asymptomatic

What is the most common secondary tumour to affect the kidney?

Lymphoma

What is the most common urinary bladder neoplasia?

Urothelial carcinoma (transitional cell carcinoma) - primary tumours are most common in the bladder

Where are urothelial carcinomas (transitional cell carcinoma) usually found?

Bladder trigone

What are the consequences of Urothelial carcinoma (transitional cell carcinoma)?

Invasive and often metastasise Predispose to infection Can cause haematuria

What is the definition of the term renal failure?

Failure of the kidneys to be able to carry out their normal excretory, metabolic and/or endocrine functions

What is acute kidney injury?

Abrupt decrease in kidney function May be reversible

What is chronic kidney disease?

Abnormalities of kidney structure and function for a long time (>3 months) Usually irreversible and often progressive

What is azotemia?

Biochemical abnormality with elevated blood urea, creatinine

What is uraemia?

Clinical SYNDROME resulting from impaired kidney function Often accompanied by multisystemic extrarenal lesions

What are the extra-renal lesions/syndromes of uraemia?

Ammonia causing caustic injury to oral and gastric epithelium - ulcer formation Uraemic toxin causing injury to blood vessel endothelium - vasculitis, thrombosis, oedema Altered calcium/phosphate metabolism - soft tissue mineralisation, secondary hyperparathyroidism, fibrous osteodystrophy Reduced erythropoietin production - anaemia

Urinary - pathology Flashcards

(76 cards)