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Flashcards in Diseases of the renal system 1 Deck (56):

What are the functions of the kidney?

- Eliminating metabolic waste products
- Regulating fluid and electrolyte balance
- Influencing acid-base balance
- Production of some hormones
-- Renin: fluid balance
-- Erythropoietin: stimulates red cell production


What is the presentation of acute renal failure?

- Rapid rise in creatinine and urea
- Generally unwell


What is the presentation of nephrotic syndrome?

- Oedema + proteinuria + hypoalbuminaemia

- Proteinuria >3g per 24h (mostly albumin)


What is the presentation of nephritic syndrome?

- Oedema
- proteinuria
- haematuria
- renal failure


What is the presentation of chronic renal failure?

Slowly declining renal function


What is the course of blood through the nephron?

- Branches of the renal artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Proximal convoluted tubule
- Vasa recta
- Distal convoluted tubule
- Branches of the renal vein


What are the immunological mechanisms of glomerular damage?

- Circulating immune complexes deposit in glomerulus
- Circulating antigens deposit in glomerulus
- Antibodies to basement membrane or other components of glomerulus

-All damage basament membrane -> Complement activation, neutrophil activation, reactive oxygen species and clotting factors -> glomerular damage


What are non-immunological mechanisms of glomerular damage?

- Injury to endothelium of vessels -> damage to vessels
- Altered basement membrane due to hyperglycaemia in diabetes
- Abnormal basement membrane or podocytes due to inherited disease
- Deposition of abnormal proteins in the kidney e.g. amyloid


What are the ischaemic mechanisms of tubular damage?

- Hypotension
- Damage to vessels within kidney
- Glomerular damage

= Reduced blood supply to tubules


What are the toxic mechanisms of tubular damage?

- Direct toxins
- Hypersensitivity reactions e.g. to drugs
- Deposition of crystals in tubules
- Deposition of abnormal proteins in the tubules


What is thrombotic microangiopathy?

- Thrombi in capillaries and small arterioles
- Due to damage endothelium
- Causes of endothelial damage include bacterial toxins, some drugs, abnormalities in complement or clotting systems
- e.g. Haemolytic uraemic syndrome


What is vasculitis?

- Acute or chronic inflammation of blood vessel walls
- obliteration of lumen by inflammation
- various different types affecting different sizes of vessel
- adults and children can be affected
- e.g. Wegener’s granulomatosis


What are the mechanisms of vascular damage to the kidney?

- Thrombotic microangiopathy
- Vasculitis
- Hypertension
- Diabetes
- Atheroma e.g. renal artery stenosis


What is always the cause of nephrotic syndrome?

Damage to glomerulus


What are the clinical features of nephrotic syndrome?

- Oedema
- Proteinuria (>3g in 24h)
- Hypoalbuminaemia
- +/- hypertension
- +/- hyperlipidaemia


What are the possible complications of nephrotic syndrome?

- Infection
- Thrombosis


What are the common pathophysiologies of nephrotic syndrome?

- Membranous nephropathy (most common)
- Focal segmental glomerulosclerosis (FSGS)
- Minimal change disease
- Other causes: diabetes, lupus nephritis, amyloid


What is membranous nephropathy?

- Idiopathic
- Primary glomerular disorder of unknown cause
- Usually adults 30-60, M>F
- 20-30% progress to end stage renal failure


What is focal segmental glomerulosclerosis (FSGS)?

- A pattern of kidney damage with various possible causes (idiopathic, genetic, heroin use, HIV. Most are idiopathic)
- M>F


What is minimal change disease?

- Biopsy is normal on light microscopy
- M=F


What are the causes of nephrotic syndrome in children?

- Minimal change disease (most common)
-- No abnormality seen on light microscopy
-- Majority of children have excellent prognosis
- Focal segmental glomerulosclerosis (FSGS)
- Other causes are rare


What are the features of acute nephritis?

- Oedema
- Haematuria
- Proteinuria
- Hypertension
- Acute renal failure


What are the common causes of acute nephritis?

- Post-infective glomerulonephritis
- IgA nephropathy
- Vasculitis
- Lupus
- Other forms of primary glomerulonephritis


What is post-infective glomerulonephritis?

- Typically occurs a few weeks after Streptococcal throat infection
- Most recover completely
- The pathophysiology of this disorder is consistent with an immune complex mediated mechanism, a type III hypersensitivity reaction.


What is IgA nephropathy?

- Most common primary glomerular disease worldwide
- Teenagers and young adults with haematuria
- 20-50% progress to renal failure over 20 years


What are the features of vasculitis?

Fever, generally unwell, may have rash, myalgia, arthralgia


What are the common causes of acute nephritis in children?

- Post-infective glomerulonephritis
- IgA nephropathy
- Henoch-Schonlein purpura
- Haemolytic-uraemic syndrome


What are the features of Henoch-Schonlein purpura?

- Specific type of IgA nephropathy, M>F
- Typically young boys/teenagers with arthralgia, abdo pain, rash, haematuria, acute renal failure
- Most recover completely


What are the features of haemolytic-uraemic syndrome?

- Typically children with E. Coli 0157 enteritis
- Acute nephritis + haemolysis + thrombocytopaenia


What are the features of acute renal failure?

anuria/oliguria + raised creatinine and urea


What is the treatment for acute renal failure?

- Short term dialysis may be needed in some patients
- Many patients will recover and have good renal function if they had healthy kidneys previously


What are the pre-renal causes of acute renal failure?

- Reduced blood flow to kidney (most common)
-- Severe dehydration
-- Hypotension e.g. Bleeding, septic shock, left ventricular failure

- Obstructed urinary tract
-- Tumours of urinary tract
-- Tumours in pelvis
-- Bladder stones
-- Prostatic enlargement

- Renal biopsy not helpful


What are the renal causes of acute renal failure?

- Damage to kidney
- Renal biopsy not helpful


What will all biopsies show in acute renal failure?

“ATN” – acute tubular necrosis/ injury/damage/acute kidney injury (ATI/ATD/AKI)


What are the causes of acute renal failure in adults?

- Vasculitis
- Acute interstitial nephritis/tubulointerstitial nephritis (tubular damage with inflammation, most commonly caused by drug reactions) – most recover


What are the causes of acute renal failure in children?

- Henoch-Schonlein purpura
- Haemolytic uraemic syndrome
- Acute interstitial nephritis


What are the possible complications of acute renal failure?

- Cardiac failure (fluid overload)
- Arrythmias (electrolyte imbalance)
- GI bleeding
- Jaundice (hepatic venous congestion)
- Infection, especially lung and urinary tract


What is the treatment for acute renal failure?

- Short term dialysis may be needed
- Treat the underlying cause


What is chronic renal failure?

Permanently reduced GFR – reduced number of nephrons


What are the stages of chronic renal failure?

Stage 1: Kidney damage with normal or increased GFR (>90 mL/min/1.73 m2)

Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m2)

Stage 3: Moderate reduction in GFR (30-59 mL/min/1.73 m2)

Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m2)

Stage 5: Kidney failure (GFR


What are the effects of chronic renal failure?

- Reduced excretion of water and electrolytes: oedema, hypertension
- Reduced excretion of toxic metabolites
- Reduced production of erythropoietin: anaemia
- Renal bone disease


What are the likely cause of haematuria +/- proteinuria with normal renal function?

- IgA nephropathy
- Thin basement membrane disease
- 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 IV cause abnormal basement membrane in the glomerulus, sometimes with eye and ear problems
- Renal failure +/- deafness +/- ocular problems
- May be autosomal or X-linked


What is 'isolate protienuria'?

Proteinuria less than the nephrotic range, without haematuria, renal failure or oedema


What are the possible causes of isolate proteinuria?

May be benign e.g. Postural, related to pyrexia or exercise.

May be due to renal disease
- Adults
-- Diabetes
-- Lupus
- Children
-- Henoch-Schonlein purpura


What is pyelonephritis?

Infection of the kidney


What are the causes and complications of acute pyelonephritis?

- Ascending infection (more common in women)
- Instrumentation of urinary tract
- Diabetics
- Structural abnormalities of urinary tract

Complications - abscess formation


What are the common causes of chronic renal failure in adults?

- Diabetes (commonest)
- Glomerulonephritis
- Reflux nephropathy


What are the common causes of renal failure in children?

- Developmental abnormalities/malformations
- Reflux nephropathy
- Glomerulonephritis


What are the causes and complications of chronic pyelonephritis?

- Most associated with obstruction of urinary tract and reflux of urine up ureter, leads to scarring of the kidney and can lead to renal failure

Complications - scarring of kidney, chronic renal failure


What are the causes and features of renal artery stenosis?

- Due to atheroma (most common) or arterial dysplasia
- Leads to ischaemia of the affected kidney
- Activation of renin-angiotensin-aldosterone system leads to hypertension
- Loss of renal tissue due to ischaemia leads to reduced renal function


What is the effect of vasculitis on the kidney?

- Inflammation can affect the glomerular vessels and lead to clotting with obliteration of capillary lumens and destruction of the glomerulus
- Inflammation of larger arterioles within the kidney can lead to hypoxia of the tubules
- Often affects other vessels around the body causing rash, muscle and joint pains
- Patients can also have fever and weight loss due to the inflammation


What is the effect of hypertension on the kidney?

- Hypertension damages renal vessels leading to thickening of the vessel wall and reduction in size of the lumen
- This produces chronic hypoxia which leads to loss of renal tubules and reduced renal function
- Reduced blood flow in the kidney leads to activation of the renin-angiotensin-aldosterone system which exacerbates hypertension


What is the effect of diabetes on the kidney?

- Diabetes is the commonest cause of end-stage renal failure in Europe and the USA
- Hyperglycaemia is the main cause of diabetic nephropathy by damaging the basement membrane
- Basement membrane becomes thicker and the glomerulus produces excess extracellular matrix which forms nodules
- Diabetes also damages small vessels leading to ischaemia and damage to renal tubules


What is the effect of myeloma on the kidney?

- Tumour of plasma cells producing immunoglobulins
- Excess immunoglobulins deposit in kidney tubules
- Tubules become damaged
- Inflammation and fibrosis of kidney occurs
- Loss of renal tubules leads to declining kidney function
- Renal impairment due to myeloma is usually irreversible

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