Diseases of the renal system 1 Flashcards
1
Q
What are the functions of the kidney?
A
- 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
2
Q
What is the presentation of acute renal failure?
A
- Rapid rise in creatinine and urea
- Generally unwell
3
Q
What is the presentation of nephrotic syndrome?
A
- Oedema + proteinuria + hypoalbuminaemia
- Proteinuria >3g per 24h (mostly albumin)
4
Q
What is the presentation of nephritic syndrome?
A
- Oedema
- proteinuria
- haematuria
- renal failure
5
Q
What is the presentation of chronic renal failure?
A
Slowly declining renal function
6
Q
What is the course of blood through the nephron?
A
- Branches of the renal artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Proximal convoluted tubule
- Vasa recta
- Distal convoluted tubule
- Branches of the renal vein
7
Q
What are the immunological mechanisms of glomerular damage?
A
- 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
8
Q
What are non-immunological mechanisms of glomerular damage?
A
- 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
9
Q
What are the ischaemic mechanisms of tubular damage?
A
- Hypotension
- Damage to vessels within kidney
- Glomerular damage
= Reduced blood supply to tubules
10
Q
What are the toxic mechanisms of tubular damage?
A
- Direct toxins
- Hypersensitivity reactions e.g. to drugs
- Deposition of crystals in tubules
- Deposition of abnormal proteins in the tubules
11
Q
What is thrombotic microangiopathy?
A
- 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
12
Q
What is vasculitis?
A
- 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
13
Q
What are the mechanisms of vascular damage to the kidney?
A
- Thrombotic microangiopathy
- Vasculitis
- Hypertension
- Diabetes
- Atheroma e.g. renal artery stenosis
14
Q
What is always the cause of nephrotic syndrome?
A
Damage to glomerulus
15
Q
What are the clinical features of nephrotic syndrome?
A
- Oedema
- Proteinuria (>3g in 24h)
- Hypoalbuminaemia
- +/- hypertension
- +/- hyperlipidaemia
16
Q
What are the possible complications of nephrotic syndrome?
A
- Infection
- Thrombosis
17
Q
What are the common pathophysiologies of nephrotic syndrome?
A
- Membranous nephropathy (most common)
- Focal segmental glomerulosclerosis (FSGS)
- Minimal change disease
- Other causes: diabetes, lupus nephritis, amyloid
18
Q
What is membranous nephropathy?
A
- Idiopathic
- Primary glomerular disorder of unknown cause
- Usually adults 30-60, M>F
- 20-30% progress to end stage renal failure
19
Q
What is focal segmental glomerulosclerosis (FSGS)?
A
- A pattern of kidney damage with various possible causes (idiopathic, genetic, heroin use, HIV. Most are idiopathic)
- M>F
20
Q
What is minimal change disease?
A
- Biopsy is normal on light microscopy
- M=F
21
Q
What are the causes of nephrotic syndrome in children?
A
- 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
22
Q
What are the features of acute nephritis?
A
- Oedema
- Haematuria
- Proteinuria
- Hypertension
- Acute renal failure
23
Q
What are the common causes of acute nephritis?
A
- Post-infective glomerulonephritis
- IgA nephropathy
- Vasculitis
- Lupus
- Other forms of primary glomerulonephritis
24
Q
What is post-infective glomerulonephritis?
A
- 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.
25
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
26
What are the features of vasculitis?
Fever, generally unwell, may have rash, myalgia, arthralgia
27
What are the common causes of acute nephritis in children?
- Post-infective glomerulonephritis
- IgA nephropathy
- Henoch-Schonlein purpura
- Haemolytic-uraemic syndrome
28
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
29
What are the features of haemolytic-uraemic syndrome?
- Typically children with E. Coli 0157 enteritis
| - Acute nephritis + haemolysis + thrombocytopaenia
30
What are the features of acute renal failure?
anuria/oliguria + raised creatinine and urea
31
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
32
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
33
What are the renal causes of acute renal failure?
- Damage to kidney
| - Renal biopsy not helpful
34
What will all biopsies show in acute renal failure?
“ATN” – acute tubular necrosis/ injury/damage/acute kidney injury (ATI/ATD/AKI)
35
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
36
What are the causes of acute renal failure in children?
- Henoch-Schonlein purpura
- Haemolytic uraemic syndrome
- Acute interstitial nephritis
37
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
38
What is the treatment for acute renal failure?
- Short term dialysis may be needed
| - Treat the underlying cause
39
What is chronic renal failure?
Permanently reduced GFR – reduced number of nephrons
40
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
41
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
42
What are the likely cause of haematuria +/- proteinuria with normal renal function?
- IgA nephropathy
- Thin basement membrane disease
- Alport type hereditary nephropathy
43
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
44
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
45
What is 'isolate protienuria'?
Proteinuria less than the nephrotic range, without haematuria, renal failure or oedema
46
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
- - FSGS
- - Diabetes
- - Lupus
- Children
- - Henoch-Schonlein purpura
- - FSGS
47
What is pyelonephritis?
Infection of the kidney
48
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
49
What are the common causes of chronic renal failure in adults?
- Diabetes (commonest)
- Glomerulonephritis
- Reflux nephropathy
50
What are the common causes of renal failure in children?
- Developmental abnormalities/malformations
- Reflux nephropathy
- Glomerulonephritis
51
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
52
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
53
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
54
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
55
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
56
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
