renal Flashcards
what are the 3 main endocrine functions of the kidneys?
- produce renin (renin-angiotensin system, increases fluid retention)
- produces erythropoetin (epo)
- activates vit D into active form
what are the 5 broad causes of vascular damage (which lead to kidney damage)?
thrombotic microangiopathy
- thrombi in arterioles/capillaries (secondary to endothelial damage - lots of causes)
vasculitis
- acute/chronic vessel wall inflammation -> narrowing of lumen
hypertension
diabetes
atheroma (eg renal artery stenosis)
what are the broad causes of glomerar damage, leading to kidney damage:
- immunological? 3
- non-immunological? 4
immunological:
- circulating immune complexes deposit in glomerulus
- circulating antigens deposit in glomerulus
- autoimmune antibodies to basement membrane/glomerular components
nb all of the immunoligcal causes lead to: - complemetn activation - neutrophil activation - reactive oxygen species - increased clotting factors which all -> glomerular damage
non-immunological:
- vessel damage/endothelial injury
- altered basement membrane
- abnormal basement membrane or podocytes due to inherited disease
- abnormal protein deposition (amyloid) impair function
give two examples of conditions which result in circulating immune complexes which deposit in the glomerulus, leading to kidney damage?
SLE
IgA/membranous nephropathy
give two examples of autoimmune conditions which consist of antibodies being created against basement membrane/glomerular components, leading to kidney damage.
goodpasture’s syndrome
- against BM in lungs + kidneys
post-infective glomerolunephritis
name a non-immunological cause of altered basement membrane
diabetes mellitus hyperglycaemia
name one inherited condition which leads to abnormal basement membrane, leading to kidney damage
alport disease/syndrome
inherited defect in type 4 collagen
leads to problems with kidneys, ears + eyes
name 3 conditions which can have abnormal protein deposition in the glomerulus, impairing function + leading to kidney damage
RA
bronchiectasis
myeloma
what is an amyloid protein?
universally used term that refers to abnormal intracellular or extracellular deposition of proteins as fibrils. Amyloid fibrils may be deposited in a variety of organs including brain, liver, heart, kidney, pancreas, nerve and other tissues as a consequence of certain inherited and acquired disorders
name 3 ischaemic causes of tubular damage + 4 toxic causes
ischaemic:
- hypotension (eg shock)
- blood vessel damage (eg vasculitis, HTN)
- glomerular damage
toxic:
- direct toxins
- hypersensitivity reactions
- crystal deposits (eg urate)
- abnormal protein deposition (eg Igs)
ischaemic causes result in reduced perfusion which leads to tubular damage (tubules are very sensitive to ischaemia!)
toxic causes directly result in tubular damage
name 4 types of drug which are nephrotoxic
- NSAIDs
- ACEi
- diuretics
- some antibiotics
name 5 non-drug compounds which are nephrotoxic
- contrast medium
- ethylene glycol (antifreeze)
- organic solvents
- pesticides
- heavy metals
nephrotic syndome:
- pathophysiology?
- 3 main features?
- 2 other possible features
- possible complications? 2
always due to damage to GLOMERULUS
- proteinuria
- oedema
- hypoalbuminaemia
(nb proteinuria results in other 2!)
+/- hypertension
+/- hyperlipidaemia
complications:
- infection
- thrombosis (as antithrombin lost in urine)
nephrotic syndrome:
- commonest cause in adults?
- 2 other common adult causes?
- 3 rarer causes in adults?
membranous nephropathy (commonest)
- idopathic primary glomerular disorder
- get thickening of basement membrane
- affect adults <60
- M>F
focal segmental glomerulosclerosis (FSGS)
- various causes (usually idiopathic, but also genetics, heroin use, HIV)
- M>F
minimal change disease
- normal histology
- diagnosis of exclusion
- M=F
(diabetes, lupus nephritis, amyloid)
what is the most common cause of nephrotic syndrome in children?
minimal change disease
- normal histology
- diagnosis of exclusion
- usually excellent prognosis
nephritic syndrome:
- alternative name?
- symptoms? 4
acute nephritis
- HAEMATURIA (norm macroscopic)
- proteinuria (less than in nephrotic)
- hypertension (slight)
- low urine output
what are 4 common causes of nephritic syndrome in adults?
post-infective glomerulonephritis:
- weeks after strep throat infection
- good recovery
IgA nephropathy
- common primary glomerular disease
- usu young adults
- 20-50% renal failure over 20 years
vasculitis
- autoimmune
lupus nephritis (caused by SLE)
- autoimmune
- usually young women
what other symptoms would someone with vasculitis have, alongside nephritic syndrome? 5
- unwell
- fever
- rash
- myalgia
- arthralgia
what are the 4 main causes of nephritic syndrome in children?
Henoch-Schönlein purpura
- a specific IgA nephropathy
- often follows throat infection
- most recover completely
haemolytic-uraemic syndrome
- typically children with e. coli gastroenteritis
post infective glomerulonephritis
IgA nephropathy
Henoch-Schönlein purpura:
- who norm affects?
- symptoms? 4
boys/teenagers
- arthralgia
- abdo pain
- purpuric rash
- proteinuria/haematuria -> acute kidney injury
haemolytic-uraemic syndrome:
- symptoms? 3
- pathophysiology?
- nephritic syndrome/acute nephritis
- haemolysis
- thrombocytopenia
norm caused by a toxin produced by e coli
- toxin damages vascular wall -> clots + haemolysis -> thrombocytopenia
get GI symptoms first, renal stuff follows
acute kidney injury (aka acute renal failure)
- definition?
- symptoms? 8
anuria/oliguria (<400ml/24hr)
+ raised plasma creatinine + urea
- malaise
- fatigue
- nausea
- vomiting
- high BP
- oedema
- confusion
- arrythmias
acute kidney injury:
- most common pre-renal causes? 2
- most common post-renal causes? 4
- when is a renal biopsy helpful?
pre-renal (norm reduced blood flow -> kidneys):
- severe dehydration
- hypotension (bleed, septic shock, LVF)
post-renal (urinary tract obstruction):
- urinary tract tumours
- pelvic tumours
- calculi (kidney stones)
- prostatic enlargement
only helpful for intra-renal causes of AKI
- imaging better for post-renal stuff
acute kidney injury:
- most common intra-renal causes in adults? 2
- most common intra-renal causes in children? 3
adults:
- vasculitis (autoimmune or inflammatory)
- acute interstitial nephritis (aka tubulointerstitial nephritis)
children:
- Henoch-Schönlein purpura
- haemolytic-uraemic syndrome
- acute interstitial nephritis
acute interstitial nephritis/tubulointerstitial nephritis:
- usual cause?
- pathophysiology?
- prognosis?
drugs
tubular damage with inflammation
most recover
acute kidney injuey:
- complications? 5
- treatment? 2
- cardiac failure (fluid overload)
- arrythmias (electrolyte imbalance)
- GI bleeding (multifactorial)
- jaundice (hepatic venous congestion)
- infection (esp lung + urinary tract)
- depends on underlying cause
- short term dialysis may be needed
nb with any fluid overload there is a resulting risk of infection
how do the kidneys regulate the acid-base balance in the body?
- excrete acid
- reabsorb bicarbonate (to greater of lesser extents)
what are 4 main groups of effects that chronic renal failure has on the body?
reduced excretion of water/electrolytes:
- > oedema
- > hypertension
reduced excretion of toxic metabolites:
- > itchy
- > confusion
- > fatigue
reduced production of erythropoetin
-> anaemia
reduced activation of vit d
-> renal bone disease
what is isolated proteinuria?
what are the possible benign causes? 3
what could it also be due to?
proteinuria BUT less than nephrotic range
- no allied haematuria, renal failure or oedema
- postural
- related to pyrexia
- related to exercise
renal disease
what does urine sample tend to look like if there is proteinuria?
frothy
isolated haematuria:
- definition?
- possible causes? 4
- investigation needed?
haematuria +/- proteinuria with NORMAL renal function
- IgA nephropathy
- thin basment membrane disease (inherited condition causing abnormally thin glomerular BM - renal function norm normal)
- alport hereditary nephropathy
- malignancy
cystoscopy/urological investigations needed to exclude malignancy
acute pyelonephritis:
- risk factors? 4
- complication?
- female (ascending infection)
- instrumentation (ie catheter)
- diabetes
- urinary tract structural abnormalities
abscess formation
chronic pyelonephritis:
- main risk factor?
- main complication?
urinary tract obstruction -> reflux
- chronic renal failure
renal artery stenosis:
- most common cause?
- other cause?
- pathophysiology?
- long term effect?
most common = renal artery stenosis
- also: arterial dysplasia
ischaemic injury of affected kidney -> activation of renin-angiotensin-aldosterone system (as kidney thinks body is hypovolemic as narrow lumen means low blood flow to kidney) -> HTN -> further damage to kidney = damage spiral
loss of renal tissue -> reduced renal function
how does hypertension cause kidney damage?
HTN -> wall thickening + reduction in lumen size
this -> chronic hypoxia
-> loss of renal tubules + reduced renal function
reduced blood flow activates renin-angiotensin-aldosterone system -> exacerbates HTN
what are the two mechanisms of kidney damage seen in diabetes mellitus?
hyperglycaemia -> damaged/thickened BM
- therefore glomerulus produces excess extracellular matrix -> nodules in kidneys which reduces function
hyperglycaemia -> small vessel damage -> ischaemia -> tubular damage
