Flashcards in Renal diseases 1 Deck (94):
What are the 4 main functions of the kidney?
1) Eliminating metabolic waste products
2) Regulating fluid and electrolyte balance
3) Influencing acid-base balance
4) Production of hormones - renin, eryhtropoietin (stimulates red cell production)
What are the 6 main presentations of renal disease?
1) Acute renal failure
2) Nephrotic syndrome
3) Acute nephritis (nephritic syndrome)
4) Chronic renal failure
Does the clinical presentation necessarily indicate the cause of renal disease?
No - each clinical presentation has a variety of causes
What are the clinical features of acute renal failure? 2
1) Rapid rise in creatinine and urea
2) Generally unwell
What 3 things make up nephrotic syndrome?
What is important about the proteinuria in nephrotic syndrome?
Must be greater than 3g per 24 hours
What are the 4 things that make up nephritic syndrome/acute nephritis?
4) Renal failure
How does chronic renal failure present?
Slowly declining renal function
What 5 disciplines are needed for diagnosis of renal disease?
1) Renal physician - clinical history and examination
2) Biochemists - blood tests and urinalysis
3) Pathologist - always light microscopy of renal biopsy, sometimes, electron microscopy and fluoroscopy in specific cases
5) Radiologist- obstruction, kidney size, structural abnormalities
When may a urologist be needed in diagnosis of renal disease?
Cytoscopy may be needed in cases of obstruction and some cases of haematuria (could be a sign of malignancy)
What blood tests and urinalysis is performed in diagnosing renal disease?
Bloods - urea, creatinine
Urine - protein, electrolytes
What are the 3 things forming the filtration barrier in the kidneys?
1) Podocyte foot processes
2) Endothelial cells
3) Basement membrane
NB. damages to any of these can impair filtration and thus renal function
What is the course of blood/ filtrate through the nephron?
1) Branches of renal artery
2) Afferent arteriole
3) Filtrate filtered out into bowman's capsule
4) Filtrate through proximal convuluted tubule
5) Through descending limb of henle, loop of henle and ascending limb of henle
6) Through distal convuluted tubule
7) All excreted filtrate through the collecting duct leading to the pelvis of the kidney
Why can damage of the glomerulus lead to damage to the tubule?
Blood flowing through the glomerulus and the efferent arteriole is the blood supplying the tubules so any damage to glomerulus could alter the blood supply to the tubules which can become ischaemic and thus damaged
What are the 2 classes of mechanisms which can damage the glomerulus?
2) Non immunological
Name 3 immunological mechanisms of damage to the glomerulus, which part specifically is damaged?
1) Circulating immune complexes deposited in the glomerulus
2) Circulating Ag deposit in the glomerulus
3) Ab to basement membrane or other components of the glomerulus produced
All of these lead to damage to the basement membrane through complement an neutrophil activation, production of reactive oxygen species and presence of clotting factors in glomerulus
Name a non immunological mechanism of damage to th glomerulus, which in particular damages the blood vessels of the glomerulus?
Injury to the endothelium of the vessels
Name 3 non immunological mechanisms of damage to the glomerulus which in particular damage the basement membrane?
1) Altered basement membrane due to hyperglycaemia in diabetes (abnormal sugars and glyocosylated proteins in blood)
2) Abnormal basement membrane or podocytes due to inherited disease
3) Deposition of abnormal proteins in the kidney eg. amyloid
What are the 2 classes of mechanisms damage to the tubules of the nephron?
What are the 3 ischaemic mechanisms of damage to the tubules of the nephron?
2) Damage to vessels within the kidney
3) Glomerular damage
All lead to reduced blood supply to the tubules and thus tubular damage
What is important about renal function in tubular damage?
The degree of tubular damage correlates well with renal function (this isnt however always the case with glomerular damage)
What are the 4 toxic mechanisms of damage to the tubules of the nephron?
1) Direct toxins
2) Hypersensitivity reactions eg. to drugs
3) Deposition of crystals in tubules (most common is gout)
4) Deposition of abnormal proteins in the tubules
Give the 5 mechanisms of vascular damage to the kidneys (blood supply to both glomerulus and tubules)?
3) Atheroma eg. renal artery stenosis
4) Thrombotic microangiopathy
Give a common cause of thrombotic microangiopathy?
Haemolytic uraemic syndrome
What is thrombotic microangiopathy?
Thrombi in the capillaries and small arterioles due to damage to the endothelium
Causes of that endothelial damage include bacterial toxins (ie this can a complication of bacterial infection), some drugs and abnormalities in complement or clotting systems
What is vasculitis?
- Acute or chronic inflammation of blood vessel walls
- Can get obliteration of lumen by inflammation
- Various different types affecting different sizes of vessel
- Can affect adults and children
Give one common type of vasculitis?
Which 3 glomerular 'diseases' can be both descriptions of the microscopic appearance due to a known cause and also disease names when the cause is unknown ie. idiopathic diseases?
All can be secondary to known cause or idiopathic diseases:
1) Membranous nephropathy
2) Focal segmental glomeruloscelrosis (FSGS)
3) Mesangiocapillary glomerulonephritis
1) proliferative glomerulonephritis
2) Crescentic glomerulonephritis
3) Thrombotic microangiopathy
appearances or diseases of the glomeruli?
Appearances secondary to known causes
Name 6 glomerular diseases (which don't describe glomerular appearances but just diseases)?
1) Minimal change disease
2) Post infective glomerulonephritis
3) Anti-GBM disease
4) IgA nephropathy
5) Henoch-Schonlein purpura
6) Lupus nephritis (SLE)
What is always the cause of nephrotic syndrome?
Always due to damage to the glomerulus
Other than the 3 defining features of nephrotic syndrome, what 2 other clinical features can be present?
What are the 2 main complications of nephrotic syndrome?
What is the most common cause of nephrotic syndrome in adults seen on renal biopsy?
Idiopathic membranous nephropathy
Which age group and gender is idiopathic membranous nephropathy most common in?
More common in males than females
Common in adults 30-60
What percentage of people with idiopathic membranous nephropathy progress to end stage renal failure?
What are the second and third most common causes of nephrotic syndrome in adults seen on renal biopsy?
2nd = focal segmental glomerulosclerosis
3rd = minimal change disease
Give 3 other causes of nephrotic syndrome in adults?
2) Lupus nephritis
What are the biopsy findings in minimal change disease, is it more common in males or females?
Same frequency in both sexes
Biopsy is normal on light microscopy
What are the 4 common causes of focal segmental glomerulosclerosis?
3) Heroin use
What is the most common cause of nephrotic syndrome in children seen on renal biopsy?
Minimal change disease - no abnormality seen on light microscopy, majority of children have excellent prognosis
What is the second most common cause of nephrotic syndrome in children, are there any other causes?
focal segmental glomerulonephritis
Other causes are rare
What is the 5th possible clinical feature of acute nephritis in addition to the 4 defining features?
What is the most common cause of acute nephritis/nephritic syndrome in adults?
1) Post infective glomerulonephritis
What are the 2nd, 3rd and 4th most common causes of acute nephritis/ nephritic syndrome in adults?
2nd = IgA nephropathy
3rd = Vasculitis
4th = Lupus
Post infective glomerulonephritis typically occurs when, what is the recovery rate?
A few weeks after streptococcal throat infection (Abs cross react)
Most recover completely
What is the most common primary glomerular disease worldwide?
Teenagers and young adults with haematuria are most likely to be suffering from which glomerular disease?
IgA nephropathy - 20-50% progress to renal failure over 20 years
What 5 other clinical features may a patient with acute nephritis due to vasculitis present with?
2) Generally unwell
3) May have rash
Lupus nephritis typically occurs in which group of people?
What are the 4 most common causes of acute nephritis in children (in order)?
1st = post infective glomerulonephritis
2nd = IgA nephropathy
3rd = Henoch-Schonlein purpura
4th = Haemolytic-uraemic syndrome
What is Henoch-schonlein purpura, who is it most common in and what are the 5 clinical features?
A specific type of IgA nephropathy
Most common in you boys/ teenage males
2) Abdo pain
5) Acute renal failure
What is haemolytic uraemic syndrome, who does it typically occur in?
Acute nephritis + haemolysis + thrombocytopaenia
Typically occurs in children whit E coli enteritis
On what basis is a diagnosis of acute renal failure made?
Anuria/oliguria + raised creatinine and urea
What is the prognosis of acute renal failure?
Many patients will recover and have good renal function if they had healthy kidneys previously
Short term dialysis may be needed in some patients
What are the 3 classes of causes of acute renal failure, in which is a renal biopsy useful?
1) Pre renal: reduced blood flow to kidney
3) Post renal: obstructed urinary tract
Biopsy only useful in renal causes
Give 5 pre renal causes of acute renal failure?
1) Severe dehydration
2) Hypotension eg.
4) septic shock
5) Left ventricular failure
What is the most common type of cause of acute renal failure?
Pre renal causes
Name 4 post renal causes of acute renal failure?
1) Tumours of the urinary tract
2) Tumours in the pelvis
3) Bladder stones
4) Prostatic enlargement
What is the treatment for acute renal failure?
1) Short term dialysis may be needed
2) Treat the underlying cause
What are the 5 possible complications of acute renal failure?
1) Cardiac failure (fluid overload)
2) Arrhythmias (electrolyte imbalance)
3) GI bleeding
4) Jaundice (hepatic venous congestion)
5) Infection, especially lung and urinary tract
What define chronic renal failure?
Permanently reduced GFR - due to a reduced number of nephrons
What are the 5 stages of chronic renal failure?
1) Kidney damage with normal or increased GFR >90ml/min/1.73m^2
2) Mild reduction in GFR (60-89)
3) Moderate reduction in GFR (30-59)
4) Severe reduction in GFR (15-29)
5) Kidney failure GFR
Which 2 stages of chronic renal failure require treatment?
Stage 4 and 5
If a patient is on dialysis which stage of chronic renal failure are they automatically at?
What are the 3 most common causes of chronic renal failure in adults?
3) Reflux nephropathy
What is reflux nephropathy?
Chronic reflux of urine up the ureter leading to repeated infections and scarring of the kidney
What are the 3 common causes of chronic renal failure in children?
1) Developmental abnormalities/malformations
2) Reflux nephropathy
Why is a renal biopsy often unhelpful in established chronic renal failure?
Similar changes are seen in end stage renal disease due to any cause
Kidney shows severe scarring with loss of glomeruli and tubules
What are the 4 main effects of chronic renal failure?
1) Reduced excretion of water and electrolytes: oedema and hypertension
2) Reduced excretion of toxic metabolites
3) Reduced production or erythropoietin: anaemia
4) Renal bone disease
What are the 2 most likely diagnosed in an elderly patient with acute renal failure?
1) Acute interstitial nephritis due to drug reactions
2) Myeloma (tumour of plasma cells secreting proteins which block up the tubules)
What is the most likely diagnosis in a young male with haematuria and a rash?
What are the 2 most likely diagnoses in a teenager/young adult with haematuria?
1) Post infective glomerulonephritis
2) IgA nephropathy
What is the most likely diagnosis in an adult with acute renal failure, fever and myalgia?
What is the most likely diagnosis in a young woman with haematuria and a facial rash?
What is the most likely diagnosis in an adult with nephrotic syndrome?
What is the most likely diagnosis in a child with nephrotic syndrome?
Minimal change disease
What investigations are needed in isolated haematuria?
Cystoscopy and other urological investigations as may be bleeding from a urinary tract tumour
What are the 3 likely renal causes of haematuria +/- proteinuria with normal renal function?
1) IgA nephropathy
2) Thin basement membrane disease
3) Alport type hereditary nephropathy
What is thin basement membrane disease?
Inherited condition causing abnormally thin basement membranes in the glomerulus - if no other renal disease present, kidney function will remain normal
What is alport type hereditary nephropathy?
Inherited abnormalities of collagen type 4 cause abnormal basement membrane in the glomerulus, sometimes with eye and ear problems
Renal failure +/- deafness/ocular problems
What is isolated proteinuria?
Proteinuria less than the nephrotic range, without haematuria, renal failure or oedema
What are the 3 likely causes of isolated proteinuria in adults?
What are the 2 likely causes of isolated proteinuria in children?
1) Henoch-schonlein purpura
What is pyelonephritis?
Infection of the kidney
What is the most common cause of chronic pyelonephritis?
Obstruction of the urinary tract and reflex of urine up the ureter
What is the main complication of acute pyelonephritis?
What are the 2 complications of chronic pyelonephritis?
1) Scarring of kidney
2) Chronic renal failure
What is the cause of renal artery stenosis?
Usually due to atheroma, can be due to arterial dysplasia
What are the 2 main complications of renal artery stenosis and why?
1) Hypertension - due to activation of RAAS
2) Reduced renal function - due to loss of renal tissue due to ischaemia
In what 2 ways does vasculitis mainly affect the kidney?
1) Inflammation can affect the glomerular vessels and lead to obliteration of capillary lumens and destruction of the glomerulus
2) Inflammation of larger arterioles within the kidney can lead to hypoxia of the tubules
How does hypertension lead to damage of the kidney?
1) Hypertension damages renal vessels leading to thickening of the vessel wall and reduction in size of lumen
2) This produces chronic hypoxia which leads to loss of renal tubules and reduced renal function
3) Reduced blood flow in the kidneys leads to activation of RAAS which exacerbates hypertension
How does diabetes damage the kidney?
1) Hyperglycaemia is the main cause of diabetic nephropathy by damaging the basement membrane
2) Basement membrane becomes thicker and the glomerulus produces excess extracellular matrix which forms nodules
3) Diabetes also damages small vessels leading to ischaemia and damage to renal tubules