Renal Flashcards
GFR is most accurately evaluated in a clinical setting via what parameter?
A) serum creatinine
B) inulin clearance
C) creatinine clearance
D) plasma clearance of radio-isotope EDTA/DTPA or iohexal
Plasma disappearance of radio isotope EDTA/DTPA or iohexal
- DMSA scan does not provide info on GFR clearance.. looks at parenchymal function, shows scarring if areas don’t light up
What is the Schwartz equation ? (Estimates GFR)
eGFR = 36.5 x height (cm) x creat (umol/L)
Not accurate in ESKD
Renin release from the juxtaglomerular cells is stimulated by:
Sodium depletion
Sympathetic stimulation
Reduced vagal stimulation
How do you differentiate between acute GN and nephrotic syndrome (minimal change disease)
Onset of oedema - acute vs gradual (GN acute)
Haematuria in nephritic
Hypertension - most acute GN present with HTN (not nephrotic)
The epithelial Na channel in the collecting duct is regulated by which hormone ?
Aldosterone
Blocked by amiloride
What are the 4 clinical features of glomerulonephritis?
Haematuria
Reduced GFR
Hypertension
Oedema (Na & H2O retention)
Which types of GN have low complement levels ?
Post-infectious
MPGN aka mesangiocapillary
SLE
What are the clinical clues pointing you towards IgA nephropathy or Alports/Thin Basement Membrane ?
“Synpharyngitic”
Gross haematuria
Family history
What is the most common cause of GN?
Post infectious GN
- age 2-12
- group A strep causing immune complex deposition
- 7-14 days post throat; later after skin
- low c3
- recurrence rare
- supportive management
What should you suspect with a history of episodes of gross haematuria at the same time as URTI??
IgA nephropathy
- IgA deposition in mesangium
- persistent microscopic haematuria
- normal complement
- can be progressive
- can not tell difference with HSP on biopsy (same disease?)
What is the most common vasculitis of childhood?
HSP Younger children 1/3 recurrence Renal involvement can occur 2 months after initial illness - weekly urine protein checks Early steroids not shown to reduce future renal involvement Treatment: Steroids, azathiprine RPGN: cyclophosphamide
What should you suspect with: adolescent girl, Indian/Maori/Pacific Islander
Low WCC
Low C3/C4
Haematuria/proteinuria
Lupus nephritis
- commonest presentation of SLE
- renal biopsy to determine class and treatment
What should you suspect with boy, haematuria & proteinuria with family history ?
Haematuria with URTI, persistent microscopic haematuria
Sensorineural hearing loss
Alports
X linked mutation of type 4 collagen (basement membrane)
Dx Electron miscroscopy of biopsy
Can progress to ESKD
Treatment with ACEI aims to delay progression - the earlier the better
What should you suspect for
Microscopic haematuria
Macro haematuria with URTI
Family members with micro haematuria
Thin basement membrane disease (aka benign familial haematuria)
Autosomal dominant
Can actually progress therefore not totally benign
What are the causes of Rapidly progressive GN?
What is the defining feature on biopsy ?
HSP
ANCA disease
Goodpastures (anti GBM)
Presence of crescents (clumps of epithelial tissue within Bowman’s capsule)
How do you differentiate between the ANCA assoc small vessel vasculotides (Wegeners vs MPO)
Wegeners
C ANCA pos
Granulomas in resp tract & kidneys
Both progress to RPGN
Treatment strong immunosuppression
Plasmaphoresis (if pulmonary haemorrhage)
What should you suspect with pulmonary and kidney involvement - pulmonary haemorrhage & crescentic nephritis
Anti GBM on serology ?
Goodpastures (aka pulmonary renal syndrome)
Caused by autoimmune complex (anti GBM) deposition in GBM
Treatment steroids, plasmapharesis, cyclophosphamide
Doesn’t recur
Which types of GN have family history?
Alports (boys)
TBM
IgA
What are the defining clinical features of nephrotic syndrome?
Proteinuria
Hypoalbuminaemia (<25g/L)
Oedema
Hyperlipidemia
What are the causes of nephrotic syndrome ?
Idiopathic (MCD 70%, FSGS, MPGN)
Hep B
Systemic inflammatory diseases (lupus, HSP)
Part of a syndrome (Denys drash, nail patella, Frasier, Pierson)
How do you define remission of nephrotic syndrome?
0/ trace albumin on Albustix for 3 consecutive days
Frequent relapsing = > 2 relapses in 6 months
Steroid dependent = 2 consecutive relapses within 2 weeks of stopping steroids
Steroid resistant = no remission after 4 weeks of steroids
What is the recommended treatment of steroid dependent nephrotic syndrome?
Cyclophosphamide
MMF
Cyclosporine
What are the complications of nephrotic syndrome?
Infection (due to low IgG, low complement, impaired lymphocyte function, immunosuppressive drugs)
Cellulitis
Bacterial peritonitis
thrombosis
How do you differentiate between CKD and AKI?
Chronic - short/stunted growth, relatively normal potassium, high phosphate, anaemia
AKI- hyperkalaemia
Both might have metabolic acidosis
What are the causes of tubular disease (acute and chronic)
Acute - tubulointerstitial nephritis
Chronic - nephronophthisis
How do you calculate the fractional excretion of sodium?
FENa = Urine Na x Plasma Cr
——————————-
Urine Cr x Plasma Na X 100%
How does FENa help distinguish between causes of renal failure?
Low FEN = prerenal AKI
High FEN = renal cause AKI (inappropriately losing Na)
What is the triad defining HUS?
Acute renal failure
Thrombocytopenia
Microangiopathic haemolytic anaemia
- raised LDH, bilirubin
- low haptoglobin
- blood film shows fragmented cells
Most common cause of AKI in western world
What are the causes of HUS?
Typical - shigatoxin E. coli
Atypical - pneumococcal pneumonia/meningitis
What type of RTA is most likely to present with hyperkalaemia?
Type IV “hyperkalaemic RTA”
Aldosterone deficiency
Causes include hypoaldosteronism, Addison’s disease, CAH
Name 3 inherited causes of Fanconi syndrome
Dent’s disease
Wilson’s disease
Galactosemia
What is the principle mechanism which ensures excretion of excess sodium when the dietary intake of salt is high?
Atrial natriuretic factor
= polypeptide hormone secreted by cardiac atria in response to atrial dilatation
- regulates blood pressure and blood volume
- inhibits renin secretion & aldosterone synthesis
- causing increased GFR and sodium excretion
- inhibits angiotensin II and noradrenaline induced vasoconstriction
- decreases desire for salt - inhibits release of ADH
- net effect = decrease in blood volume/pressure
In Alports sydnrome, what is the risk of developing ESKD for x linked homozygotes?
85%
Which structure derives from the ureteric bud ?
Collecting duct
What effect do thiazides have on calcium ?
Low calcium in urine
What is the diagnosis ? Immunofluorescence positive for IgG, IgA, IgM, C3, C1q
SLE
What is the mechanism of action of loop diuretics ?
Inhibits Na K Cl2 cotransporter
Causes hypo Na, K, Mg
Gout
what is the mechanism of action of thiazides ?
Distal convoluted tubule
Inhibits Na Cl cotransporter (NCCT)
What is the mechanism of Amiloride?
K sparing diuretic
Blocks ENaC
Late distal tubule collecting duct
Inhibits Na reabsorption and K excretion
What is the mechanism of action of spironolactone?
Inhibits aldosterone
K sparing diuretic
Inhibits K secretion
What is the diagnosis ?
Gross haematuria and HTN post skin infection
IgG and C3 on IF
Subepithelial jumps on EM
Post strep GN
What is the diagnosis ? Recurrent gross haematuria Assoc with URTI Fam hx IgA mesangial deposits on IF Normal C3
IgA nephropathy
What is the inheritance and genetics of Alports syndrome ?
X linked
COL4A5 mutation
Type 4 collagen
What is the diagnosis ? Recurrent gross haematuria on bg asymptomatic microscopic Anterior lenticonus EM splitting and laminated GBM Normal C3
Alports
What is the diagnosis ? Teenage girl Nephritic syndrome Full house on IF Low C3
Lupus nephritis
What is the inheritance and genetics of Thin Basement membrane disease ?
Autosomal dominant
COL4A mutation
Fam hx microscopic haematuria
What is the diagnosis ?
Pulmonary haemorrhage and anti GBM antibodies
Goodpastures
What is the diagnosis ?
Granuloma in resp tract
cANCA pos
GPA
Aka wegeners
Minimal change disease is steroid responsive true or false
True
98%
If not - more likely FSGS
What is the mechanism behind hypercoagulability as complication of nephrotic syndrome ?
Reduced antithrombin III
And protein C and S
What are the encapsulated organisms?
Strep Neisseria Klebsiella Haemophilus Salmonella Cryptococcus Pseudomonas E. coli some strains
What is the mechanism of action of levimasole?
Anti helmithic
Immunodulator
Used for frequent relapsed nephrotic syndrome
What is the mechanism of action of cyclosporine ?
Calcineurin inhibitor
Used for steroid dependent nephrotic syndrome
What stimulates aldosterone secretion and what does it do?
Angiotensin II (hyper K) Stimulates aldosterone release from adrenal medulla Causes de novo synthesis of Na K ATPase to increase Na retention and K excretion
NB spironolactone inhibits aldosterone
What are the effects of angiotensin II?
Stimulates aldosterone secretion from adrenal medulla
ADH secretion from posterior pituitary
Renal arteriolar vasoconstriction
Sympathetic activity
All results in Na, H2O retention
Increased perfusion of JG apparatus
Increased circulating blood volume
What is the diagnosis ? Proximal RTA (impaired bicarb reabsorption) HypoPO4 Hypoglycaemia Hypoproteinaemia
Fanconi’s syndrome
Great with sodium bicarbonate
Postassium citrate
What type of RTA
- hypoK, hypercalcinuria - stones
Type 1
Distal tubular
Inhibition of H excretion
What type of RTA?
HyperK
Type 4
Aka hypoaldoseronism
How do you differentiate between Bartters and Gitelman’s?
Barrters acts like a loop diuretic Causes hypoK, hypercalinuria - stones Gitelmans acts like a thiazides Causes hypoK and more pronounced hypoMg Presents later in life, more mild
Batters bad
Gitelmans good
At what stage of CKD do you get bone disease and anaemia ?
Stage 3 (GFR 30-60)
Bone disease
Low Ca due to low Vit D causes increased PTH - osteoclast activity
Also increase PO4
Stage 4 - GFR 15-29
Anaemia
Due to low production EPO
Acidosis
What is the mechanism of action of tacrolimus?
Calcineurin inhibitor
What is the mechanism of action of sirolimus?
mTOR inhibitor
Inhibits repose to Il2
(Cell proliferation)
What is the mechanism of action of basilizumab?
Anti IL 2
What is the mechanism of action of mycophenylate?
Inhibits purine synthesis
Suppresses B and T cell proliferation
What is the mechanism of action of azarhioprine?
Purine analogue causing cell cycle arrest
What renal imaging is used to exclude PUJ?
MAG3 - tracer should clear, if not - obstructed
What is the best renal imagine for scarring ?
DMSA
How do you differentiate between juvenile nephronopthisis and ARPKD?
JN - small echogenic kidneys on US
Normotensive (chronic hypovolaemia)
ARPKD - large echogenic kidneys, microcysts enlarge over time; always assoc with hepatic fibrosis (massive intrahepatic bilary duct dilatation on US)
How do you differentiate between central and nephrogenic DI?
Both have low urine urine lamp on water deprivation test
- dDAVP stimulation
Urine osmo will increase for central (deficiency of ADH but ability to concentrate urine is intact)
Urine osmo unchanged for nephrogenic (inability to concentrate urine despite adequate amounts ADH)
