Renal: Nephrotic Syndrome & Nephritis Flashcards
What is nephrotic syndrome?
Note - this is a syndrome not a condition (i.e. other conditions cause it).
When the basement membrane in the glomerulus becomes highly permeable to protein, allowing proteins to leak from the blood into the urine.
What age is nephrotic syndrome most common?
Between 2-5 y/o
What classic triad is seen in nephrotic syndrome?
1) Hypoalbuminaemia (< 30g/L)
2) Proteinuria (>3+ protein on dipstick)
3) Oedema
What serum albumin level is seen in nephrotic syndrome?
Hypoalbuminaemia <30 g/L
What proteinuria level is seen in nephrotic syndrome?
≥3.5 g/day
What causes oedema that is seen in nephrotic syndrome?
Hypoalbuminaemia results in reduced oncotic pressure, causing oedema.
What 3 other features are seen in nephrotic syndrome?
1) Deranged lipid profile: high levels of cholesterol, triglycerides and low density lipoproteins (LDLs)
2) HTN
3) Hypercoagulability
Symptoms of nephrotic syndrome?
1) Peripheral oedema (more common in adults)
2) Facial oedema (more common in children)
3) Frothy urine
4) Fatigue
5) Poor appetite
6) Recurrent infection (due to immune dysfunction)
7) Venous or arterial thrombosis (e.g. MI, DVT) due to hypercoagulability
Clinical signs of nephrotic syndrome?
1) Oedema (e.g. peri-orbital, lower limb, ascites)
2) Xanthelasma and/or xanthoma
3) Leukonychia
4) SOB (with associated chest signs of pleural effusion – e.g. stony dullness in lung bases)
Typical urinalysis findings in nephrotic syndrome?
1) Proteinuria (protein ++++)
2) Frothy appearance
Pathophysiology of nephrotic syndrome?
1) Damage to the glomerular basement membrane and podocytes –> increased permeability to proteins (proteinuria).
2) Proteinuria then results in hypoalbuminaemia –> subsequent oedema due to reduced plasma oncotic pressure.
3) Loss of antithrombin-III, proteins C and S and an associated rise in fibrinogen levels predispose to thrombosis
4) Loss of thyroxine-binding globulin lowers the total, but not free, thyroxine levels.
What is the most common cause of nephrotic syndrome in children?
Minimal change disease.
This can occur in otherwise healthy children, without any clear risk factors or reason for developing the condition.
What will a renal biopsy and standard microscopy in minimal change disease?
Usually not able to detect any abnormality.
What will urinalysis show in minimal change disease?
1) Small molecular weight proteins
2) Hyaline casts
Management of minimal change disease?
Corticosteroids i.e. prednisolone.
Prognosis of minimal change disease?
The prognosis is good and most children make a full recovery, however it may reoccur.
What is the most common underlying cause in a 2 – 5 year old child with oedema, proteinuria and low albumin?
Nephrotic syndrome caused by minimal change disease.
What are 3 primary causes of nephrotic syndrome?
1) Minimal change disease
2) Focal segmental glomerulosclerosis (FSGS)
3) Membranous nephropathy
What are some 2ary causes of nephrotic syndrome?
1) Diabetes mellitus
2) SLE
3) Amyloidosis
4) Infections (HIV, Hep B and C)
5) Drugs (NSAIDs, gold therapy)
Investigations in nephrotic syndrome?
1) Urine dipstick: proteinuria and check for microscopic haematuria
2) MSU: exclude UTI
3) Quantify proteinuria –> use an early morning urinary protein:creatinine ratio or albumin:creatinine ratio.
4) FBC and coagulation screen
5) U&Es
What are 2 ways of quantifying proteinuria?
1) early morning urinary protein:creatinine ratio
2) albumin:creatinine ratio
What is the uribne albumin:creatinine ratio (ACR) in nephrotic syndrome?
High i.e. ≥250
General management of nephrotic syndrome?
1) High dose prednisolone
2) Low salt diet
3) Diuretics may be used to treat oedema
4) Albumin infusions may be required in severe hypoalbuminaemia
5) Antibiotic prophylaxis may be given in severe cases
How long are high dose steroids given for in nephrotic syndrome?
4 weeks, and then gradually weaned over the next 8 weeks.
In nephrotic syndrome, what dose ‘steroid sensitive’, ‘steroid dependent’, and ‘steroid resistant’ mean?
Steroid sensitive: 80% of children will respond to steroids
Steroid dependent: Patients that struggle to wean steroids due to relapses
Steroid resistant: Patients that do not respond to steroids
What are some complications of nephrotic syndrome?
1) Oedema
2) Hypotension
3) Thrombosis
4) Infection
5) AKI or CKD
6) Relapse
What % of patients will have a relapse in nephrotic syndrome?
80%
What causes hypotension in nephrotic syndrome?
Hypovolaemia occurs as fluid leaks from the intravascular space into the interstitial space, causing oedema and low BP.
What causes thrombosis in nephrotic syndrome?
1) Proteins that normally prevent blood clotting are lost in the kidneys
2) The liver responds to the low albumin by producing pro-thrombotic proteins
What causes a predisposition to infections in nephrotic syndrome?
The kidneys leak immunoglobulins, weakening the capacity of the immune system to respond.
This is exacerbated by treatment with medications that suppress the immune system, such as steroids.
What is nephritis?
Inflammation within the nephrons of the kidneys
What 5 classic signs are seen in nephritic syndrome?
1) Haematuria (either visible or detectable on urinalysis)
2) Mild to moderate proteinuria (typically <3.5 g/L) i.e. less than nephrotic syndrome
3) HTN
4) Oliguria (<300 mls/day)
5) Oedema
What 3 things are seen on urinalysis in nephritic syndrome/nephritis?
1) Haematuria (blood +++)
2) Proteinuria (mild - protein ++)
3) Red cell casts
What is the distinguishing feature of nephritic syndrome on urinalysis?
Red cell casts
What are the 2 most common causes of nephritis in children?
1) Post-strep glomerulonephritis
2) IgA nephropathy (Berger’s disease).
What is post-strep glomerulonephritis?
A glomerular condition mediated by an immunological response to a group A streptococci (GAS) infection.
What infection does post-strep glomerulonephritis follow?
Group A streptococci (GAS) i.e. Strep. pyogenes
E.g. tonsillitis caused by Streptococcus pyogenes
How soon after strep infection does post-strep glomerulonephritis typically occur?
Depends on the site of infection:
- 1-3 weeks for pharyngitis
- 3-6 weeks for skin infection
What is the most commonly affected age group for post-strep glomerulonephritis?
5-12 y/o
An increased risk also present for older adults >60years.
Are boys or girls more affected by post-strep glomerulonephritis?
Boys (2x)
Pathophysiology of post-strep glomerulonephritis?
Immune complexes made up of streptococcal antigens, antibodies & complement proteins get stuck in the glomeruli of the kidney and cause inflammation.
This inflammation leads to an acute deterioration in renal function, causing an AKI.
What is the most commonly recognised clinical presentation of post-strep glomerulonephritis?
Nephritic syndrome:
1) Generalised oedema
2) HTN
3) Haematuria
4) Oliguria (due to decline in renal function)
Note - Rarely, some cases can present, with rapidly progressive glomerulonephritis, with a rapid deterioration in kidney function towards kidney failure within weeks.
What causes HTN in nephritic syndrome?
Caused by water and salt retention due to renal insufficiency.
What causes oedema in nephritic syndrome?
Caused by water and salt retention due to renal insufficiency.
This can progress to severe complications of fluid overload, eg. respiratory distress due to pulmonary oedema.
What causes haematuria in nephritic syndrome?
Red blood cell components leak from glomerular capillaries through the damaged glomerular membrane into the urine.
What colour does urine typically appear in nephritic syndrome?
Urine looks tea or cola-coloured due to haematuria.
Key investigations in post-strep glomerulonephritis?
1) Urinalysis
2) U&Es: can show a variable degree of decline of eGFR and elevated creatinine
3) Culture (throat or skin swab to confirm the presence of GAS)
4) Serology
5) Renal biopsy
Purpose of urinalysis in post-strep glomerulonephritis?
1) Confirm haematuria
2) Quantify degree of proteinuria
Purpose of serology in post-strep glomerulonephritis?
Testing for antibodies against GAS can be helpful to confirm a recent infection using the Streptozyme test.
What is the Streptozyme test?
A combined test measuring the levels of the 5 antibodies that can be produced in response to a recent GAS infection e.g. Anti-streptolysin (ASO).
What investigation can provide a definitive diagnosis of post-strep glomerulonephritis?
renal biopsy - but due to the self-limiting clinical course of PSGN, a biopsy is rarely needed.
Management of post-strep glomerulonephritis?
Mainly supportive and focused on managing coomplications that arise from fluid overload.
1) Sslt & water restriction
2) Diuretics
3) Monitor BP
4) Monitor renal function
5) Abx if there is any evidence of a persistent streptococcal infection
What are some potential short-term complications of post-strep glomerulonephritis?
1) Pulmonary oedmea
2) Hypertensive encephalopathy
3) Severe AKI requiring dialysis
Prognosis of post-strep glomerulonephritis
Most cases in children resolve with no long-lasting effects.
What are some causes of transient or spurious non-visible haematuria?
1) UTI
2) Menstruation
3) Vigorous exercise (usually settles after 3 days)
4) Sexual intercourse
What are some causes of persistent non-visible haematuria?
1) Cancer (renal, bladder, prostate)
2) Stones
3) BPH
4) Prostatitis
5) Urethritis e.g. Chlamydia
6) Renal causes: IgA nephropathy, thin basement membrane disease
What are some spurious causes of haematuria (i.e. red/orange urine, where blood is not present on dipstick)
1) Foods: beetroot, rhubarb
2) Drugs: rifampicin, doxorubicin
What are 2 drugs that can cause discoloured urine?
1) Rifampicin
2) Doxorubicin
Who should be urgently referred under the 2 week wait in regard to haematuria?
Aged ≥45 y/o AND:
1) unexplained visible haematuria without UTI, or
2) visible haematuria that persists or recurs after successful treatment of UTI
Aged ≥60 y/o AND have unexplained nonvisible haematuria and either dysuria or a raised white cell count on a blood test.
Give some causes of haematuria
1) Trauma e.g. blunt injury
2) Infection (remember TB!!)
3) Malignancy
4) Renal disease e.g. Glomerulonephritis
5) Stones
6) Structural abnormalities e.g. BPH
7) Coagulopathy: causes bleeding of underlying lesions
8) Drugs
9) Benign: exercise
10) Gynaecological e.g. endometriosis
11) Iatrogenic e.g. catheterisation, radiotherapy
12) Pseudohaematuria
What infection is it important to consider in haematuria?
TB
What is the most common type of urothelial malignancy?
Transitional cell carcinoma –> painless haematuria.
What drugs can cause haematuria?
1) Cause tubular necrosis or interstitial nephritis –> aminoglycosides, chemotherapy
2) Cause interstitial nephritis –> penicillin, sulphonamides, and NSAIDs
3) Anticoagulants
Define glomerulonephritis
Inflammation of the glomeruli in the kidneys.
This damage allows protein (with or without blood) to leak into the urine.
Note - glomerulonephritis describes the pathology that occurs in various diseases rather than being a disease.
What is the glomerulus?
The first part of the nephron. It filters fluid out of the capillaries and into the renal tubule.
Give some ways the glomerulonephritis present
1) Isolated haematuria or proteinuria
2) Nephrotic syndrome
3) Nephritic syndrome
4) Acute renal failure
5) Chronic renal failure
What can glomerulonephritis be broadly categorised into?
Proliferative & non-proliferative
What is the definition of nephrotic syndrome?
Massive proteinuria (≥3.5 g/day) and hypoalbuminaemia (serum albumin ≤30 g/L).
What is non-proliferative glomerulonephritis characterised by?
A lack of glomerular cell proliferation.
How does non-proliferative glomerulonephritis typically present?
With nephrotic syndrome
What are the 3 types of non-proliferative glomerulonephritis?
1) Minimal change glomerulonephritis
2) Focal segmental glomerulosclerosis (FSGS)
3) Membranous glomerulonephritis
How does minimal change glomerulonephritis present?
With nephrotic syndrome.
Accounts for 80% of all nephrotic syndrome in children and 20% of nephrotic syndrome in adults.
What is the underlying cause of minimal change glomerulonephritis?
The underlying cause is unknown.
The name minimal change glomerulonephritis comes from the lack of changes seen on light microscopy.
What is the main histological finding in MCD?
Diffuse effacement of the podocyte foot processes (essential structures for maintaining the integrity of the glomerular filtration barrier).
This effacement occurs without significant immune complex deposition or thickening of the glomerular basement membrane.
What are the 3 key features of MCD?
Nephrotic syndrome:
1) Oedema
2) Proteinuria
3) Hypoalbuminaemia
How does oedema in MCD typically present?
- Periorbital puffiness
- Lower extremity swelling
- Ascites (severe cases)
What causes oedema in MCD?
1) Hypoalbuminaemia (decreases plasma oncotic pressure) –> due to proteinuria
2) Renal sodium retention (due to altered glomerular filtration)
What amount of protein is lost in the urine in MCD?
≥3.5 grams daily
What causes hypoalbuminaemia in MCD?
excessive urinary protein loss
What other possible features are seen in MCD?
1) Hyperlipidaemia
2) Haematuria
3) Renal insufficiency (AKI/CKD)
4) Infections
5) Thromboembolic events
What can cause hyperlipidaemia in MCD?
Due to increased hepatic synthesis of lipoproteins in response to hypoalbuminaemia.
Hyperlipidemia is also linked to a higher risk of atherosclerosis.
Describe haematuria in MCD
Microscopic haematuria may be present in a minority of MCD patients but is typically not a prominent feature.
If gross hematuria is observed, other diagnoses should be considered.
Why are patients with MCD at increased risk of infection?
Due to immunosuppressive treatment and the loss of immunoglobulins in the urine.
Infections include RTIs, cellulitis, and peritonitis.
Why are thromboembolic events more common in MCD
Due to hypercoagulable state induced by nephrotic syndrome.
what investigations are indicated in MCD?
1) Urinalysis: proteinuria (& maybe haematuria)
2) Blood tests: U&Es, albumin, lipod profile
3) Renal US
4) Renal biopsy
Investigation for definitive diagnosis in MCD?
Renal biopsy (note - in children, this is generally avoided)
What can electron microscopy show in MCD?
Diffuse loss of visceral epithelial cells’ foot processes (i.e. podocyte effacement).
1st line management of MCD?
Corticosteroids
What is 2nd line for MCD (in steroid-resistant cases)?
Cyclophosphamide
Prognosis of MCD?
Prognosis is overall good, although relapse is common.
1/3 have just one episode
1/3 have infrequent relapses
1/3 have frequent relapses which stop before adulthood
What is the most common cause of nephrotic syndrome in adults?
Focal segmental glomerulosclerosis (FSGS)
What is FSGS?
A cause of nephrotic syndrome and chronic kidney disease.
It generally presents in young adults.
Who does FSGS usually present in?
Young adults
What can FSGS be divided into?
1ary: unknown cause with a possible genetic element
2ary: caused by another disease process, e.g. HIV, lupus, reflux nephropathy
What can FSGS occur 2ary to? (5)
1) other renal pathology e.g. IgA nephropathy, reflux nephropathy
2) HIV
3) Heroin
4) Alport’s syndrome
5) Sickle-cell
Focal segmental glomerulosclerosis is noted for having a high recurrence rate in who?
Renal transplant
What are the common clinical features associated with FSGS? (5)
1) Nephrotic syndrome: proteinuria, hypoalbuminaemia, oedema &H hyperlipidaemia
2) Proteinuria
3) Haematuria
4) HTN
5) Renal insufficiency
Describe hypoalbuminemia level in nephrotic syndrome
<3 g/dL
What is the key investigation in FSGS? What is the finding?
Renal biopsy:
- Segmental scarring of some glomeruli
- Fusion of foot processes
Management of FSGS?
High-dose prednisolone +/- immunosuppressants (e.g. cyclophosphamide or ciclosporin)
Prognosis of FSGS?
Typically progresses to end-stage kidney disease over the course of several years in up to 50% of patients.
Corticosteroids can halt progression in some cases.
What is the commonest type of glomerulonephritis in adults?
Membranous glomerulonephritis
How does membranous glomerulonephritis usually present?
With nephrotic syndrome or proteinuria
Causes of membranous glomerulonephritis?
- Usually idiopathic –> due to anti-phospholipase A2 antibodies
- Infections: hep B, malaria, syphilis
- Malignancy: lung cancer, lymphoma, leukaemia
- Drugs: gold, penicillamine, NSAIDs
- Autoimmune: SLE, thyroiditis, rheumatoid
Pathophysiology in membranous glomerulonephritis?
Immune complex deposition results in complement activation against glomerular basement membrane proteins.
Clinical features of membranous glomerulonephritis?
1) Nephrotic syndrome: proteinuria, oedema, hyperlipidaemia, hypoalbuminaemia
2) HTN
3) Infection susceptibility
4) Renal insufficiency
5) Haematuria (microscopic)
How does proteinuria typically present?
Frothy urine
Key investigation in membranous glomerulonephritis?
What does it show?
Renal biopsy
Microscopic analysis –> shows thickened glomerular basement membrane –> ‘spike and dome’ appearance
Immunofluorescence –> shows diffuse uptake of IgG
What does management of membranous glomerulonephritis typically involve?
Supportive care: salt restriction and fluid management
Corticosteroids
Prognosis of membranous glomerulonephritis?
The rule of thirds:
1/3 have chronic membranous glomerulonephritis
1/3 go into remission
1/3 progress to end-stage renal failure
How does non-proliferative glomerulonephritis vs proliferative glomerulonephritis present?
Non-proliferative glomerulonephritis –> presents with nephrotic syndrome
Proliferative glomerulonephritis –> presents with nephritic syndrome.
What is proliferative glomerulonephritis characterised by?
Increased number of cells in the glomerulus.
What are the 5 types of proliferative glomerulonephritis?
1) IgA nephropathy
2) Post-infectious glomerulonephritis
3) Membranoproliferative glomerulonephritis
4) Rapidly progressive glomerulonephritis (crescentic glomerulonephritis)
5) Anti-glomerular basement membrane antibody disease (Anti-GBM)
6) Vasculitic disorders
What is IgA nephropathy also known as?
Berger’s disease
What is the commonest cause of glomerulonephritis worldwide?
IgA nephropathy (also known as Berger’s disease)
How does IgA nephropathy classically present?
As MACROscopic haematuria in young people 24-48 hours after an URTI.
What 3 conditions are associated with IgA nephropathy?
1) Alcohlic cirrhosis
2) Coeliac disease/dermatitis herpetiformis
3) Henoch-Schonlein purpura
Clinical features of IgA nephropathy?
- typically young male, recurrent episodes of macroscopic haematuria
- typically associated with mucosal infections e.g. URTI
What is the key differential for IgA nephropathy?
Post-streptococcal glomerulonephritis
What is the main symptom in post-streptococcal glomerulonephritis?
Proteinuria (although haematuria can occur)
What is the main symptom in IgA nephropathy?
Haematuria
Post-streptococcal glomerulonephritis is associated with low levels of what?
Low complement levels
Key differences between IgA nephropathy and post-strep glomerulonephritis? (3)
1) Longer latency period between URTI and PSGN than IgA nephropathy.
2) Proteinuria dominates in PSGN, haematuria dominates in IgA nephropathy.
3) PSGN typically doesn’t recur, IgA nephropathy can
How soon after URTI does post-strep glomerulonephritis typically occur?
1-2 weeks after
How soon after URTI does IgA nephropathy typically occur?
1-2 days after
Investigations & their findings in IgA nephropathy?
1) Renal biopsy:
- Increased numbers of mesangial cells
- Increased matrix (the cellular scaffolding that holds everything together)
2) Immunohistochemistry –> IgA deposition in the matrix
What does management of IgA nephropathy involve?
1) High-dose prednisolone: can reduce proteinuria and delay renal impairment
2) Other immunosuppressive drugs: can be used in patients with deteriorating renal function
Prognosis of IgA nephropathy?
Prognosis is variable, with 20 – 30% of patients progressing to end-stage renal failure.
Markers of GOOD prognosis in IgA nepropathy? (1)
Frank haematuria
Markers of POOR prognosis in IgA nepropathy? (5)
1) Male gender
2) Proteinuria (especially >2g/day)
3) HTN
4) Smoking
5) Hyperlipidaemia
What is post infectious glomerulonephritis?
an immunologically mediated glomerular injury triggered by an infection.
What is post infectious glomerulonephritis most commonly associated with?
Streptococcal infections (post-streptococcal glomerulonephritis)
How soon after strep infection does post-streptococcal glomerulonephritis typically present?
2 weeks after
How does post-strep glomerulonephritis present?
With nephritic syndrome i.e. gross haematuria, HTN, oligura & oedema.
What organism is implicated in post-strep glomerulonephritis?
Group A Strep
What is the most commonly affected age group with post-strep glomerulonephritis?
5-12 y/o
Pathophysiology of post-strep glomerulonephritis?
1) Throat or skin GAS infection
2) Production of antibodies against streptococcal antigens
3) Nephritogenic streptococcal antigens become lodged in glomerular membrane
4) Anti-streptococcal antibodies bind to form immune complexes
5) Activation of complement and inflammation
6) Damage to glomerulus
7) Clinical features of PSGN
Clincial features of post-strep glomerulonephritis?
- History of GAS infection (pharyngitis or skin infection)
2) Acute nephritis syndrome:
- generalised oedema
- HTN
- gross haematuria
- oliguria
What causes generalised oedema in post-strep glomerulonephritis?
Caused by water and salt retention due to renal insufficiency.
What can generalised oedema in post-strep glomerulonephritis progress to?
Severe complications of fluid overload e.g. respiratory distress due to pulmonary oedema.
What causes HTN in post-strep glomerulonephritis?
Caused by water and salt retention due to renal insufficiency.
Cause of gross haematuria in post-strep glomerulonephritis?
RBC components leak from glomerular capillaries through the damaged glomerular membrane into the urine.
How does urine appear in post-strep glomerulonephritis?
Tea or cola-coloured
Investigations in post-strep glomerulonephritis?
1) Urinalysis: confirm haematuria and quantify the degree of proteinuria (usually mild)
2) Renal function tests
3) Culture: throat or skin swab
4) Serology
5) Complement
6) Renal biopsy
Why may serology be helpful in investigating post-strep glomerulonephritis?
Testing for antibodies against GAS can be helpful to confirm a recent infection.
What serology test can be done in post-strep glomerulonephritis?
The Streptozyme test
What is the Streptozyme test?
A combined test measuring the levels of the following 5 antibodies that can be produced in response to a recent GAS infection:
1) Anti-streptolysin (ASO)
2) Anti-hyaluronidase (AHase)
3) Anti-streptokinase (ASKase)
4) Anti-DNase B
5) Anti-nicotinamide-adenine dinucleotidase (anti-NAD)
Complement levels in post-strep glomerulonephritis?
Low C3 levels found during intitial 2 weeks
How can a definitive diagnosis of post-strep glomerulonephritis be made?
Renal biopsy
Why is a renal biopsy in post-strep glomerulonephritis rarely needed?
Due to self-limiting clinical course of the disease.
Renal biopsy is usually only indicated where there is diagnostic uncertainty to confirm the diagnosis and to exclude differential diagnoses.
What are 2 key features on renal biopsy in post-strep glomerulonephritis?
1) Diffuse proliferative and exudative glomerular histology
2) Dominant C3 staining and subepithelial humps
What is the key differential for post-strep glomerulonephritis?
IgA nephropathy
Management of post-strep glomerulonephritis?
Management is largely supportive, with careful monitoring of fluid balance.
1) monitor BP
2) monitor renal function
3) Abx therapy if there is any evidence of a persistent streptococcal infection
What can reduce the incidence and severity of PSGN?
Early Abx therapy
What are 3 possivle short term complications of post-strep glomerulonephritis?
1) Pulmonary oedema
2) Hypertensive encephalopathy
3) AKI
Prognosis of post-strep glomerulonephritis?
PIGN is usually a self-limited disease, especially in children.
What is membranoproliferative glomerulonephritis?
A group of immune mediated disorders characterised histologically by glomerular basement membrane thickening, proliferative changes on light microscopy and immune complex deposition.
What is membranoproliferative glomerulonephritis characterised histologically by?
1) Glomerular basement membrane thickening
2) Proliferative changes on light microscopy
Membranoproliferative glomerulonephritis vs membranous glomerulonephritis?
Membranoproliferative glomerulonephritis –> involves mesangial cell proliferation
Membranous glomerulonephritis –> basement membrane is thickened, but the mesangium is not.
What conditions is membranoproliferative glomerulonephritis associated with?
Hep C
Autoimmune conditons e.g. SLE
Typical findings on renal biopsy in membranoproliferative glomerulonephritis? (3)
1) Thickened basement membrane
2) Thickened mesangium
3) “Tram tracking” appearance
What does immunofluorescence show in membranoproliferative glomerulonephritis?
Subendothelial deposition of IgG.
What does management of membranoproliferative glomerulonephritis involve in children?
Corticosteroids
What does management of membranoproliferative glomerulonephritis involve in adults?
Dipyridamole and aspirin
What is anti-glomerular basement membrane antibody disease (Anti-GBM)?
An immune-mediated pathology involving antibodies directed against glomerular basement membrane antigens (anti-GBM antibodies).
These antigens are located in the glomeruli and in the alveoli of the lungs.
If the lungs and kidneys are involved the condition is known as Goodpasture’s syndrome.
Renal biopsy findings in Anti-GBM disease?
IgG deposits along the basement membrane of the glomerulus
What antibodies are seen in anti-GBM disease?
Anti-GBM antibodies
Management of anti-GBM disease?
High dose immunosuppression e.g. IV prednisolone, cyclophosphamide and plasmapheresis.
2 key features of anti-GBM disease?
1) pulmonary haemorrhage
2) rapidly progressive glomerulonephritis:
- this typically results in a rapid onset AKI
- nephritis → proteinuria + haematuria
What is one of the main complications of anti-GBM disease?
Pulmonary haemorrhage
What are some factors that increase the likelihood of pulmonary haemorrhage in anti-GBM disease?
- smoking
- LRTIs
- pulmonary oedema
- inhalation of hydrocarbons
- young males
What is lost through the kidneys to produce a hypercoagulable state in nephrotic syndrome?
Antithrombin III proteins (body’s anticoagulants)
What is lost through the kidneys in nephrotic syndrome to leave patients at a higher risk of infection?
Immunoglobulins
On urinalysis in nephrotic syndrome, there may be fatty casts. What are these?
Hyaline from dead epithelial cells that contained fat globules.
What causes hyperlipidaemia in nephrotic syndrome?
Lipids are lost through kidneys.
Liver increases lipoprotein synthesis in response –> hyperlipidaemia.
Nephrotic syndrome can be 1ary or 2ary.
What does 1ary mean?
Due to direct sclerosis of podocytes on the glomerulus.
What are the 3 causes of 1ary nephrotic syndrome?
1) Minimal change disease
2) Focal segmental glomerulosclerosis
3) Membranous nephropathy
What can minimal change disease be triggered by?
- recent infection
- recent vaccination
- immune stimulus e.g. bee sting
Pathophysiology of minimal change disease?
T cells in blood release cytokines (glomerular permeability factor) that damages the foot processes of the podocytes (effacement - making them flat).
Damaged foot processes then let albumin through into urine but NOT larger molecules like immunoglobulins.
In minimal change disease, there is SELECTIVE proteinuria in contrast to other causes of nephrotic syndrome.
What does this mean?
Damaged foot processes in MCD let albumin through but not larger molecules e.g. immunoglobulins.
What is the only investigation that allows you to see changes in MCD?
Electron microscopy –> effacement of podocyte foot processes.
What is the only nephrotic disease that can be consistently treated with corticosteroids?
MCD
What is the most common cause of nephrotic syndrome in individuals of African or Hispanic descent?
FSGS
What is typically seen in history in FSGS?
- history of heroin abuse
- HIV
- interferon treatment
- congenital malformations
What is major antigen found in the serum of individuals with membranous nephropathy?
IgG antibodies against PLA2R (phospholipase A2 receptor)
What is seen on light microscopy in membranous nephropathy?
Diffuse capillary & GBM thickening caused by immune complex deposition.
What are the immune complexes made up of in membranous nephropathy?
IgG & C3
What causes a ‘spike and dome’ appearance in membranous nephropathy?
There are thin expansions of the GBM that separate or surround the immune complexes, creating a ‘spike and dome’ pattern.
How can diabetes cause 2ary nephrotic syndrome?
When there is a lot of glucose in the blood, it can stick to proteins in the blood.
This thickens efferent arteriole –> increases pressure (i.e. harder for blood to leave).
Afferent arteriole dialetes.
Increased pressure leads to increase in glomerular filtration rate (hyperfiltration).
What is seen on light microscopy in nephrotic syndrome 2ary to diabetes (i.e. diabetic glomerulonephropathy)?
1) Mesangial expansion
2) GBM thickening
3) Kimmelstiel-Wilson nodules
How can diabetic glomerulonephropathy be screened for?
Screening for microalbuminuria
What are 2 systemic diseases that can cause 2ary nephrotic syndrome?
1) diabetic glomerulonephropathy
2) amyloidosis
What are the 3 features of renal failure in nephritic syndrome?
1) oliguria
2) arterial HTN (due to Na+ retention)
3) peripheral & periorbital oedema
Disorders that can cause nephritic syndrome can be separated into what 3 main categories?
1) Caused by type III hypersensitivity:
- post-strep glomerulonephritis (PSGN)
- IgA nephropathy
- diffuse proliferative glomerulonephritis
2) Multiple potential causes:
- membranoproliferative glomerulonephritis
- rapidly progressive glomerulonephritis
3) Alport syndrome
What causes Alport syndrome?
A defect in collagen synthesis
What skin infection can cause PSGN?
Impetigo
Pathophysiology in PSGN?
Antibodies (IgG and IgM) form immune complexes with bacterial antigen –> deposit in GBM.
This initiates an inflammatory reaction in the glomerulus –> activation and deposition of C3 complement, cytokines, oxidants and proteases that damage podocytes.
How is C3 affect in PSGN?
Low levels of C3 in blood
What is seen on immunofluorescence in PSGN?
IgG, IgM and C3 deposits along the GBM and mesangium –> ‘starry sky’ appearance.
How does age affect prognosis in PSGN?
Children - often resolves on its own
Adults - can lead to renal failure
Pathophysiology in IgA nephropathy>
Abnormal IgA form inthe body, immune system recognises them as foreign.
Body generates IgG Abs that target these IgAs –> forms immune complexes –> get lodged in kidney –> activate complement pathway.
Results in glomerular injury.
What are IgA Abs mainly secreted by?
Mucosal tissue of respiratory & GI tract.
Therefore, IgA nephropathy usually accompanies a respiratory or GI infection.
What is diffuse proliferative glomerulonephritis usually caused by?
SLE
What 2 infections can cause membranoproliferative glomerulonephritis?
Hep B or Hep C
These release circulating immune complexes that reach the glomerulus.
What is a type III hypersensitivity reaction?
A type of immune response in which antigen-antibody complexes accumulate in the tissues and cause inflammation and tissue damage.
What are the 3 types of
Type 1 - Goodpasture disease (anti-GBM disease)
Pathophysiology in anti-GBM disease (Goodpasture disease0?
Anti-GBM antibodies target collagen IV in GBM.
This activates complement system –> damages GBM in kidney AND also damages alveoli in lungs (leading to haemoptysis).
Pathophysiology in Alport syndrome?
Mutation in type IV collagen gene –> GBM becomes thin and splits.
What are 2 key features of Alport syndrome?
1) Can cause hearing loss in late childhood/adolescence
2) Retinopathy & lens dislocation
