Pathology of Glomerulus and tubules and nephrotic syndrome Flashcards
What is Amyloidosis
Extracellular deposition of amyloid (eosinophilic, homogeneous and proteinaceous material)
Kidney is probably the organ most commonly involved
Usually glomerular, but medullary location predominates in cats and Shar-Pei dogs
Most common form:Reactive systemic amyloidosis (AA amyloid) – chronic Ag stimulation
CLINICALLY: Chronic renal insufficiency and proteinuria (nephrotic syndrome)
What is amyloid
a misfolded, abnormal proteinaceous material that is most commonly caused by chronic inflammation such as arthritis or irritable bowel syndrome
when amyloid gets lodged in the filter, it becomes permanently open and can no longer function. Inflammation produces high levels of serum amyloid A
what is nephrotic syndrome
Damage to glomerular filtration barrier => leakage of various low MW proteins (e.g. albumin) into glomerular filtrate => overload of protein reabsorption capabilities of the PC tubules => protein-rich glomerular filtrate accumulates in tubules => protein in urine
Renal diseases that result in proteinuria = protein-losing nephropathies (one of several causes of severe hypoproteinaemia in animals)
Prolonged, severe renal protein loss => hypoproteinaemia, <plasma colloid osmotic (oncotic) pressure=> Nephrotic Syndrome
Features and clinical signs of nephrotic syndrome
Characterized by generalised oedema, ascites, pleural effusion, and hyperlipidaemia (hypercholesterolemia)
Clinical signs: proteinuria (albuminuria), hypoproteinaemia (hypoalbuminaemia), hyperlipidaemia, generalised oedema
Why does nephrotic syndrome result in oedema
due to decreased plasma colloid osmotic pressure, stimulation of the renin-angiotensin-aldosterone system, and release of antidiuretic hormone (ADH) in response to hypovolaemia
Hepatic response to hypoproteinaemia - generalized increase in production of proteins, including lipoproteins => hyperlipoproteinemia and hypercholesterolemia
What is glomerulonephritis
Inflammation of glomeruli with secondary tubulointerstitial and vascular changes
Common in domestic animals
Damaged glomerular filtration barrier – proteinuria (protein-losing nephropathy)
Common causes of glomerulonephritis
Deposition of immune complexes (antigen-antibody)
Persistent antigenemia
Viral infections->(FeLV, FIV, FIPV, canine adenovirus type 1, EIAV, BVDV,…)
Chronic bacterial infections->(pyometra, pyoderma…)
Chronic parasitism->(dirofilariasis, leishmaniasis, trypanosomiasis, Encephalitozoon cuniculi…)
Neoplasia
What is glomerulosclerosis
Glomerulus so damaged that it becomes scar tissue
Chronic glomerulonephritis evolves glomerulosclerosis
Histology: Shrunken, eosinophilic and hypocellular glomeruli
Proteinuria, in absence of urinary tract inflammation, is indicative of glomerular damage
What is thrombosis
Blood clot
Causes and consequences of acute tubular necrosis
Hypoxia/ischaemia:
Hypotension: hypovolaemic shock, cardiogenic shock, severe dehydration…
Nephrotoxicity:
Lead, aminoglycosides, tetracyclines, monensin (antibiotics), NSAIDs, oak, Ochratoxin A (from fungi), Vitamin D, ethylene glycol (antifreeze), cisplatin (chemotherapy drug), myoglobin, haemoglobin…
Consequences:Acute renal failure or chronic interstitial nephritis (possible chronic renal failure)
What is involved in tubulointerstitial nephritis
The interstitium and tubules
Why does nephrotic sydrome lead to hyperlipaemia
Hyperlipidemia in nephrotic syndrome caused by:
Increased liver synthesis of lipids in response to hypoproteinaemia
Decreased clearance of lipids by damaged kidneys
Altered lipid metabolism due to decreased albumin level in blood
What is EIAV
equine infectious anaemia virus
