Renal Flashcards
Goodpasture’s syndrome overview
Rapidly progressing acute nephritic syndrome leading to renal failure, antibodies against specific type IV collagen types within alveolar basement membrane and glomerular basement membrane
Also known as anti-glomerular basement membrane disease
Goodpasture’s syndrome investigations
LM - crescentic GN
Immunofluoresence - continuous linear deposition of IgG along GBM
Serum anti-GBM Ab, normal C3
IgA nephropathy investigations
(Follows viral infections)
LM - focal proliferation
Immunogluorescence - diffuse mesangial IgA
EM - mesangial deposits
Lupus nephritis overview
Range of presentations, varying from haematuria and/or proteinuria to nephritic/nephrotic syndrome
Involves immune complex deposition
Lupus nephritis investigations
LM and immunofluorescence - varying in severity but related to immune complex deposits (Ig, C3) in mesangium/subendothelial layers
Increased ANCA, anti-dsDNA, decreased C3 and C4
Mesangiocapillary GN overview
Presents with anything from asymptomatic haematuria/proteinuria to acute nephritic/nephrotic syndrome
Type 1: circulating immune complexes trapped in glomerular sub endothelial space
Type 2: derangement of complement regulation
Low serum C3
‘Tram-tracking’ appearance
Post-infectious GN overview
Acute nephritic syndrome (gross haematuria, oedema, HT, renal insufficiency) 1-2 weeks post strep pharyngitis or 3-6 weeks post strep pyoderma
Mediated by immune complexes ?glomerular deposition/complement activation by directly deposited strep antigens
Post-infectious GN investigations
LM - diffuse proliferation, increased neutrophils
Immunofluorescence - granular, “hump-like” sub epithelial IgG and C3
EM - sub epithelial humps
Decreased C3-C9, normal C1 and C4, increased ASOT/antiDNAse B
Alport syndrome overview
Hereditary disease of collagen IV (part of glomerular BM)
Hereditary nephritis - microscopic haematuria (macroscopic 1-2 days after infections), proteinuria frequently
Sensorineural deafness - high frequency initially and progressive
EM - variable thickness of basement membrane with splitting
Benign familial haematuria overview
Refers to isolated haematuria in multiple family members without renal dysfunction
IgA nephropathy follow up?
Ongoing follow up for life indicated due to ESRF in 25% of patients 15-20 years after disease onset
IgA nephropathy poor prognostic factors
Hypertension, proteinuria
As GFR declines, urinary creatinine clearance overestimates GFR due to what mechanism?
As GFR declines, an increasing proportion of creatinine is secreted by the tubules, resulting in an overestimation
Physiological changes associated with HIV associated nephropathy?
Focal segmental glomerulosclerosis seen in 65% of patients
Antiretroviral therapy induces remission in most cases, but rarely HIVAN can occur in patients with well controlled HIV
Most common cause of nephrotic syndrome in children?
Minimal change disease, especially in 1-10 year olds
Membranoproliferative GN overview
Most common in second decade
Can be primary or secondary
Can present with nephrotic syndrome, nephritic syndrome, or persistent microscopic haematuria and proteinuria
Causes of secondary MPGN?
Infections such as Hepatitis B or C, syphilis, or subacute bacterial endocarditis
Treatment for post infectious GN?
Rest, fluid restriction
Loop diuretic e.g. frusemide
- if resistant to frusemide, use hydralazine or nifedipine
ACEi effective but usually not used due to hyperkalaemia risk
Best treatment for moderate hypertension following post-infectious GN?
Frusemide
If resistant, try hydralazine or nifedipine
Most likely teratogenic consequence of ACEi/ARB in pregnancy?
Renal insufficiency is the most common Cx of intrauterine ACEi/ARB exposure
Limb defects are also a complication, in 17% of neonates exposed after 20 weeks
Risk of long term hypertension following UTI is related to?
Presence/degree of renal scarring
Best method of assessing renal scarring?
Renal scintigraphy using DMSA (dimercaptosuccinic acid)
- DMSA is injected IV, and uptake by the kidney is measured 2-4 hours later
- areas of reduced uptake suggest pyelonephritis (acute) or scarring (chronic)
What does DTPA (diethylenetriamine pent-acetic acid) scan show?
Used to assess differential renal function, and when frusemide is given, drainage/obstruction can also be measured
What is IV pyelogram used for?
Looks for evidence of renal tract obstruction
Micturating cysto-urethrogram (MCU) is the best test for?
Test of choice to establish the presence and degree of VUR, but will not detect renal scarring
Distal renal tubular acidosis overview
RTA type 1 = distal renal tubular acidosis
Defective H+ secretion from the distal tubule
Low K+, sometimes low Na+
Hypercalciuria
Positive urinary anion gap (Na + K - Cl)
AR and AD forms
Proximal renal tubular acidosis overview
RTA type 2 = proximal renal tubular acidosis overview
Wasting HCO3-, inability to reabsorb
Low K+, normal Na+
Normal urine calcium
Fanconi’s biochemical findings
Low serum phosphate, uric acid
Increased urine glucose, amino acids, LMW proteins
How is Alport syndrome most commonly inherited?
X linked (mutations in COL4A5 gene)
Can also be AR (15%, mutations in COL34A3 or COL4A4) or AD (up to 5%, mutations in COL4A3 or COL4A4)
What is the mechanism to explain low serum Na in patients with marked hyperglycaemia?
The increase in serum glucose raises the serum osmolality, which pulls water out of cells and lowers the serum sodium concentration (pseudohyponatraemia)
Addison’s disease overview
Autoimmune adrenal insufficiency - deficiency of mineralocorticoids
Causes hyponatraemia, low bicarb and chloride, hyperkalaemia
What is the first step of management in DKA?
Fluid resuscitation to replace losses from polyuria and vomiting, and to avoid shock
Resuscitation fluids are always normal saline
Melnick Fraser syndrome overview
Also known as branchio-oto-renal syndrome
AD disorder with complete penetrance
Occurs in 1 in 40,000, associated with mutations in EYA1 and SIX1 and SIX5 genes
Not all children have renal lesions, may have 1-2 features only
Preauricular pits
Features of rhabdomyolysis
Raised CK (usually >5000mmol/L), mainly CK-MM rather than CK-MB
Raised creatinine and potassium
Muscle pain, dark urine due to myoglobinuria
Also usually associated with hypovolaemia, hyperphosphataemia, hypocalcaemia, raised urea and a metabolic acidosis
Management of rhabdomyolysis
Hydration
Sodium bicarbonate (to prevent renal failure from accumulation of myoglobin and irate crystal in the tubules)
Diuretics to improve urinary flow
ECG monitoring
DIC management
Dialysis if oliguric renal failure
Surgery if required for compartment syndrome
Late complications include cardiac issues from hyperkalaemia, AKI, compartment syndrome and DIC
Rhabdomyolysis overview
Occurs due to muscle necrosis where the intracellular muscle constituent are released into the circulation
What is the gold standard investigation for renal artery stenosis?
Renal arteriography
What is the most common cause of renal artery stenosis in children?
Fibromuscular dysplasia
Best pre-operative imaging for Wilms tumour?
MRU (magnetic resonance urography) - gives a more detailed assessment of renal anatomy
Presentation with acute renal failure and sterile pyuria?
Acute interstitial nephritis
Presentation of acute tubular necrosis?
Muddy brown casts and heme.
Patients are usually oedematous
Diabetes insipidus impact on kidneys
Deficiency of ADH, leads to inappropriately dilute urine leading to dehydration
Recommendations for bilateral renal pelvis dilatation?
Bilateral dilatation of >10mm suggests very high likelihood of underlying pathology (bladder outlet obstruction, severe reflux etc)
Should have ultrasound within first week of life, earlier if there is reduced urinary output
What is the most common cause of hypertension in patients with neurofibromatosis?
Essential hypertension
Renal artery stenosis is more common in children with neurofibromatosis
Treatment for minimal change nephrotic syndrome
High dose daily steroid for 6 weeks, then alternate day for 4 weeks, then tapered over 1-2 months
If ongoing proteinuria on daily steroids = steroid resistant and needs renal biopsy
If relapses whilst on alternate day steroid OR relapses within 28 days of successful steroid course = steroid dependent
If responds well to steroids but relapses >4 times per year = frequent relapsers
If steroid dependent, frequent relapser or steroid resistant, consider alternative therapies
Clinical triad of HUS
Microangiopathic haemolytic anaemia, thrombocytopenia and acute renal failure
Link between VUR and hypertension?
Of a study of patients with VUR, children with renal scarring were at risk of hypertension, and those without scarring did not develop hypertension
Liddle syndrome overview
Monogenic AD disorder causing increased expression of epithelial sodium channels in the distal nephron (resulting in increased sodium resorption, therefore features similar to hyperaldosteronism)
Serum aldosterone levels are typically low
Typically presents in second or third decade of life
Microscopic haematuria and proteinuria, hypertension, creatinine 88, EM shows thick and thin “basket weave” pattern of the BM
Alport syndrome - common cause of chronic microscopic haematuria
Can also affect vision and hearing
COL4A3/COL4A4/COL4A5 genes can be affected
Features of nephronophthisis
Reduced urinary concentrating ability with a bland urinary sediment
Chronic tubulointerstitial nephritis and progression to end-stage renal disease (usually by 20 years)
Poor growth may be related to dehydration initially, then due to CKD
Normal BP and normal sized kidneys
Denys-Drash syndrome triad
Infantile nephrotic syndrome due to diffuse mesangial sclerosis, Wilms tumour and 46 XY
46 XX patients have normal external genitalia but may have streak gonads or bicornuate uterus
Disorder due to mutation in WT1 gene at 11p13
Features of WAGR syndrome
Wilms tumour
Aniridia
Genitourinary abnormalities (cryptorchidism and/or hypospadias, could have ambiguous genitalia)
Intellectual Disability (previously retardation)
Chronic renal failure due to FSGS occurs in 60%
Decreased afferent arteriole pressure leads to…
Increased renin = increased angiotensin II = increased aldosterone
Decreased atrial stretch leads to…
Decreased ANP
Increased vasopressin
Overview of ADH (vasopressin)
Produced by hypothalamus, secreted by posterior pituitary
Released in response to decreased atrial pressure (i.e. hypovolaemia)
Kidney causes increased water reabsorption by increasing permeability in collecting duct, producing more concentrated urine
The predominant cause of anaemia in chronic renal failure?
Decreased production of erythropoietin
Causes of anaemia in CRF - decreased EPO production, iron/folate/B12 deficiency, decreased EPO survival
Calculation for fractional excretion of sodium?
(Urine Na / Urine Cr) x (Plasma Cr / Plasma Na) x100
Up and salt (urine first then plasma, salt first)
In a child with suspected multi cystic dysplastic kidneys, which is the most appropriate imaging?
DTPA or Mag3
DTPA is an excretory nuclear medicine scan which assesses obstruction
Following treatment of nephrotic syndrome (presumed post-infective), what pathology result would indicate consideration of renal biopsy?
Hypocomplementaemia
Persistent low C3/C4 raises suspicion for MPGN
Features of infantile nephronophthisis
Rare disorder, most severe form of nephronophthisis (usually results in ESRF by 12 months)
Caused by mutations in NPHP2 and NPHP3
Severe hypertension is common (unlike older forms where hypertension not usually seen)
Renal imaging shows normal kidneys with cysts
Extra-renal findings in 80% of patients
Can be detected antenatally with oligohydramnios/renal abnormalities
Action of aldosterone?
Increases reabsorption of sodium by acting primarily on principal cells in collecting ducts
Responsible for sodium reabsorption and subsequent water conservation
Action of angiotensin II?
Produces arteriolar constriction, increases SBP and DBP
Very potent vasoconstrictor
Also acts on adrenal cortex to increase secretion of aldosterone
Action of anti-diuretic hormone?
Causes retention of water by increasing permeability of collecting ducts
Urine becomes more concentrated and volume decreases
Osmolality of body fluid decreases
Action of prostaglandin I2?
Unstable cyclooxcygenase metabolite found in vascular endothelial cells
Potent vasodilator and inhibitor of platelet aggregation
Action of thromboxane?
Promotes platelet aggregation and vasoconstriction
Activated in acute severe blood loss to constrict bleeding vessels and form clot
During acute hypovolaemia, which mediator produces dilation of the renal afferent arteriole?
Prostaglandin (can dilate or constrict)
Likely would cause dilation of the renal afferent arteriole, whilst angiotensin II constricts the efferent arteriole
What embryological structure develops into the adult kidney?
Metanephros - arises from the nephrogenic cord as a metanephric diverticulum which grows into the nephrogenic cord to form a metanephric blastema
Complications of primary VUR?
Pyelonephritis, reflux nephropathy and ESRD
Rate of spontaneous resolution of low grade VUR diagnosed in infancy?
80%
Definition of grade I VUR
Reflux into the ureter but not into the collecting system
Definition of grade II VUR
Reflux into the ureter and collecting system WITHOUT dilatation
Definition of grade III VUR
Reflux into the ureter and collecting system with mild ureteric and renal pelvis dilatation
Definition of grade IV VUR
Reflux fills and grossly dilates the ureter and collecting system, causing ureteric tortuosity and significant blunting of the calyces
Definition of grade V VUR
Reflux fills and grossly dilates the ureter and collecting system, with blunted calyces and loss of papillary impressions, and intrarenal reflux may be present
Hypokalaemic metabolic alkalosis with hypercalcuria, high urinary chloride, normal BP?
Bartter syndrome
Metabolic alkalosis, hypokalaemia, high urinary chloride, normal BP?
Occult diuretic use
Hypokalaemia, ?hypernatraemia (due to water loss), water depletion, metabolic alkalosis?
Occult laxative use
Urinary loss of potassium, chloride, hypokalaemia, metabolic alkalosis?
Hyperaldosteronism (common cause of secondary hypertension)
Low/normal BP, loss of chloride, metabolic alkalosis, hypokalaemia, hypochloraemia with urinary chloride close to zero, secondary hyperaldosteronism and renal loss of potassium?
Self-induced vomiting
Which of the following is least likely to lead to a progression of chronic renal failure?
Hyperlipidaemia, hypocalcaemia, metabolic acidosis, phosphate retention, proteinuria
Hypocalcaemia
Proteinuria -> renal function decline
Hypertension -> causes arteriolar nephrossclerosis and increases hyperfiltration injury
Phosphate retention -> leads to calcium-phosphate deposition in the renal interstitial and blood vessels
Hyperlipidaemia -> oxidant-mediated injury
Factors that result in progressive renal failure?
Hyperfiltration injury
Persistent proteinuria
Systemic or infrarenal hypertension
Renal calcium-phosphorus deposition
Hyperlipidaemia
What is hyper filtration injury?
Final common pathway of glomerular destruction (independent of the underlying cause of renal injury)
Remaining nephrons undergo structural and functional hypertrophy, with increased blood flow
What cells are produced as a result of exposure to high levels of urea?
Burr cells - short and evenly separated spikes over the surface of the red blood cell
Primary site of action of thiazide diuretics?
Proximal portion of the distal tubule
Mechanism of action of thiazide diuretics?
Sodium reabsorption via the Na-Cl cotransporter is blocked through competition with the Cl site of the cotransporter
Impact of thiazide diuretics on calcium levels?
Can enhance reabsorption of calcium ions through a direct action on the early distal tubule, therefore useful agents to reduce calciuria in patients with kidney stones
Impact of thiazide diuretics on magnesium levels?
Magnesium excretion is increased by thiazides, which may result in hypomagnesemia
What electrolyte imbalances are expected from chronic thiazide diuretic use?
Hyponatraemia
Hypochloraemic alkalosis
Hypokalaemia
Hypomagnesaemia (although magnesium can be normal)
Other less common side effects from thiazide diuretic use?
Hypercalcaemia, hyperglycaemia, hyperuricaemia and gout, rash and photosensitivity, altered plasma lipids, pancreatitis, neutropenia and thrombocytopenia, intrahepatic cholestasis, acute renal failure
Primary causes of nephrotic syndrome?
Minimal change disease (most common)
Focal segmental GN
Membranoproliferative GN
Membranous nephropathy
Diffuse mesangial proliferation
Secondary causes of nephrotic syndrome?
SLE
HSP
Malignancy (lymphoma, leukaemia)
Infections (hepatitis, HIV, malaria)
Triad of clinical findings associated with large urinary losses of protein?
Hypoalbuminaemia
Oedema
Hyperlipidaemia
What is AD thin glomerular basement membrane nephropathy?
Diffuse thinning of GBM
One of the most common causes of isolated haematuria
Exact prevalence and prognosis unclear, usually considered a benign cause of haematuria with usually no effect on renal function
Indications for MCUG?
VUR in children (recurrent UTI)
Stress incontinence
Urethral stricture
Bladder dysfunction
Contraindications for MCUG
Current UTIs
Contrast media allergies
Most common cause of severe obstructive uropathy in children?
Posterior urethral valves
Classic triad of renal vein thrombosis?
Thrombocytopenia
Haematuria
Flank mass
(Most patients do not experience all 3 signs)
Pneumococcal can lead to anaemia, thrombocytopenia and renal dysfunction due to what pathological process?
Haemolytic uraemic syndrome
How is a diagnosis of pneumococcal related HUS made?
AKI
Microangiopathic haemolytic anaemia
Thrombocytopenia
Treatment of HUS
IV fluids
Transfusion of WASHED packed red blood cells
Dialysis
Plasmapheresis