Renal System 1 Flashcards
What is the function of the kidneys?
- Eliminating metabolic waste
- Regulating fluid & electrolyte balance
- Influencing acid-base balance
- Production of some hormones (renin, erythropoietin)
How do patients with renal disease present?
- Acute renal failure= generally unwell, rapid rise in creatinine & urea
- Nephrotic syndrome= Oedema, proteinuria & hypoalbuminaemia
- Acute nephritis= Oedema, proteinuria, renal failure & haematuria
- Chronic renal failure= slow decline in renal function
In the kidneys, what element allows filtration?
Podocytes, endothelial cells & basement membrane
What can cause damage to the kidney basement membrane? What does this ultimately lead to?
- Circulating immune complexes & antigens deposit in glomerulus
- Lupus nephritis
- IgA nephropathy
- Anti- GBM disease
- Antibodies to basement membrane or other components
- All lead to complement & neutrophil activation & reactive O2 species and clotting factors causing glomerular damage
What non-immunological mechanisms can cause glomerular damage?
Damage to vessel- Injury to endothelium of vessels, altered bm due to hyperglycaemia in DM
Damage to BM- Abnormal bm or podocytes due to inherited disease, deposition of abnormal proteins in the kidney (amyloid)
What ischaemic factors can lead to tubular damage?
- Hypotension/ shock
- Damage to vessels within kidney
- Glomerular damage
- All lead to reduced blood supply to tubules
What toxic factors can lead to tubular damage?
- Direct toxins
- Hypersensitivity reactions (drugs)
- Deposition of crystals or abnormal proteins in tubules
- All lead to direct tubular damage
What factors can cause vascular damage to the kidneys?
- Hypertension
- Diabetes
- Atheroma (renal artery stenosis)
- Vasculitis
- Thrombotic microangiopathy
How does vasculitis damage blood vessels in the kidneys?
- Acute/chronic inflammation of vessel walls
- Obliteration of lumen by inflammation of glomerular vessels leading to clotting & destruction of glomerulus
- Different types affect different vessels
- Inflammation of larger arterioles within kidney can lead to hypoxia of tubules
- Often affects other vessels so rash, joint & muscle pain
- E.g Wegener’s granulomatosis
How does thrombotic microangiopathy lead to vascular damage in the kidneys?
- Thrombi in capillaries & small arterioles
- Due to damaged endothelium by bacterial toxins, drugs, abnormalities in complement or clotting system
- E.g Haemolytic uraemic syndrome
Give the: -Complications -Signs -Causes of nephrotic syndrome
Causes= always due to damage to glomerulus- membranous nephropathy, FSGS, minimal change disease, other Signs= Oedema, proteinuria (>3g), hypoalbuminaemia Comp= infection, thrombosis
What are the signs of acute nephritis?
- Oedema
- Haematuria
- Proteinuria
- Hypertension
- Acute renal failure
What are the causes of acute nephritis in adults &children?
A=
Post-infective glomerulonephritis
(after strep throat, complete recovery)
IgA nephropathy (upto 50%= renal failure, teens/y.adults w/ haematuria)
Vasculitis (fever, unwell, rash, myalgia, arthralgia)
Lupus (autoimmune, y.women)
C=Post-infective glomerulonephritis
IgA nephropathy
Henoch-Schonlein purpura (Specific IgA nephropathy, y.boys w/abdo pain, arthralgia,rash, haematuria, acute renal failure)
Haemolytic-uraemic syndrome (E.Coli infection, acute nephritis, haemolysis, thrombocytopaenia)
How is acute renal failure diagnosed?
Anuria/oliguria & raised creatinine & urea
What are the causes of acute renal failure? (outside of the kidney)
Pre-renal= reduced blood flow to kidneys, severe dehydration, hypotension (septic shock, bleeding, LVF)- renal biopsy not helpful Post-renal= tumours in pelvis or urinary tract, bladder stones, prostatic enlargement- renal biopsy helpful Intrinsic= damage to the glomeruli, renal tubules, or interstitium
What are causes of acute renal failure within the kidney?
Adults=Vasculitis, Acute interstitial nephritis (by drug reactions)
Children= Acute interstitial nephritis, Henoch-Schonlein purport, Haemolytic uraemic syndrome
What are complications of acute renal failure and how is it treated?
- Cardiac failure (fluid overload)
- Arrythmias (electrolyte imbalance)
- GI bleeding
- Jaundice (hepatic venous congextion)
- Infection
- Short term dialysis & treat underlying cause
What are causes of chronic renal failure?
Adults= Diabetes, glomerulonephritis, reflux nephropathy Children= glomerulonephritis, reflux nephropathy, developmental abnormalities/malformations
What are the effects of chronic renal failure?
-Reduced excretion of H2O & electrolytes= oedema & hypertension
-Reduced excretion of metabolites
-Renal bone disease
-Reduced production of erythropoietin= anaemia
Describe acute pyelonephritis and its complications
- More common in women& diabetics
- Bacterial lower UTI which tracks back up to the kidneys
- Abscess formation
Describe chronic pyelonephritis and its complications
- Most associated with obstruction of urinary tract & reflux of urine
- Leads to scarring of kidneys and can lead to chronic renal failure
Describe renal artery stenosis
- Due to atheroma or arterial dysplasia
- Leads to ischaemia of affected kidney
- Activation of renin-angiotensin-aldosterone system= hypertension
- Loss of renal tissue due to ischaemia= reduced renal function
How does hypertension damage the kidneys?
- Damages renal vessels
- Leads to thickening of vessel wall & reduction in lumen size
- Produces chronic hypoxia leading to loss of renal tubules & reduced renal function
- Reduced blood flow in kidney activates renin-angiotensin-aldosterone system exacerbating hypertension
How does diabetes damage the kidneys?
- Commonest cause of end stage renal failure
- Hyperglycaemia main cause of diabetic nephropathy by damaging basement membrane
- BM becomes thicker & glomerulus produces excess ECM which forms nodules
- Also damages small vessels leading to ischamia & damage to renal tubules
How does a myeloma damage the kidneys?
- Tumour of plasma cells producing immunoglobulins
- Excess deposited in kidney tubules
- Tubules become damaged & inflamed & fibrosis occurs
- Loss of renal tubules leads to decline in kidney function
- Renal impairment usually reversible
Clinical presentation of glomerulonephritis
Nephrotic=Proteinuria, oedema, hypoalbuminaemia, hyperlipidaemia
Nephritic=Haematuria, hypertension, proteinuria, low urine volume
What are primary and secondary causes of nephrotic syndrome?
- 1=minimal-change nephropathy, membranous nephropathy, and focal glomerulosclerosis
- 2=diabetes mellitus, lupus erythematosus, and amyloidosis.
What are primary and secondary causes of nephritic syndrome?
- 1=IgA nephropathy, Post-streptococcal glomerulonephritis
- 2=Vasculitis, Goodpasture’s, SLE, Hep B&C
What are the clinical features & causes of interstitial nephritis?
-Cause= drug effects/allergy, hypokalaemia, hypercalcaemia/ uric acid, infection, autoimmune (SLE, kawasaki, wegener)
-Features=haematuria, fever
Inc/dec urine, Mental changes,
Nausea/vomiting, rash, swelling/oedema
Describe inherited kidney disease
- ADPKD or ARPKD
- fluid-filled cysts develop, multiply and grow in kidneys
- abdo pain, recurrent UTI haematuria, kidney stones & kidney failure
- may have cysts in liver, pancreas, spleen, ovaries, and large bowel
