Renal Flashcards by Catherine Hawco

What stimulates the release of renin from the juxtaglomerular cells?

Renal artery hypotension
Reduced sodium delivery to distal tubule
Stimulation by the sympathetic nervous system

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What effect does Angiotensin 2 have in the RAAS system?

Acts directly on the kidney
- Na and water retention

Acts on smooth muscle
- vasoconstriction

Acts on the adrenal glands to release Aldosterone
- Na and water retention at the collecting ducts

Acts on the pituitary to release ADH
- Na and water retention at collecting ducts

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What is the classic triad of Haemolytic Uraemic Syndrome?

Acute Kidney Injury
Haemolytic Anaemia
Thrombocytopenia

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What are the clinical and investigative features of HUS?

Prodrome of gastro with bloody diarrhoea
Haematuria, oliguria
Dehydration

Haemolytic anaemia
 - Coombes negative, schistocytes
AKI
Haematuria with RBC casts + dysmorphic cells
Low grade proteinuria

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What are the clinical features of Membranoproliferative GN?

Peak incidence 5-15 yrs

Acute nephritic syndrome
- Haematuria, Hypertension, AKI

Varying proteinuria

May present with rapidly progressive GN

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What are the diagnostic features of Membranoproliferative GN?

Low complement levels

Type 1 C3 + C4
Type 2 C3 only

Diagnosis by renal biopsy
- C3 (+/- C4) deposits on IF

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Features differentiating PSGN vs Membranoproliferative GN

PSGN is more common
Nephrotic syndrome not present with PSGN
In PSGN C3 normalises within 6-8 weeks

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Pathogenesis of SLE Nephritis?

Immune complex mediated

Autoantibodies bind to the glomeruli and cause direct damage

Alterations in the innate immunity cause amplification of inflammation

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What are the clinical features of SLE Nephritis?

Adolescent females

Most common is Proliferative Nephritis

significant proteinuria
hypertension
active lupus serology

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What are the extra renal manifestations of SLE?

Anaemia
Malar rash
Synovitis/arthritis 
Photo sensitivity rash 
Serositis eg. Pleuritis, carditis
Neurological involvement eg. Seizures, psychosis

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Diagnostic investigations of SLE Nephritis?

Renal biopsy

Low C3 and C4 levels (persistant)
ANA +ve
Autoantibodies - lupus anticoagulant,
anti-DsDNA, anti-Sm

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What is the pathophysiology of anti-GBM disease?

Small vessel vasculitis

Antibodies directed against type 4 collagen in Alveoli, glomeruli

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How does anti-GBM disease present?

Rare in children - peak incidence 20s and 60s

Rapidly progressive GN

Haematuria with casts + dysmorphic cells
Hypertension
Proteinuria (not nephrotic range)
AKI

Haemoptysis and Pulmonary haemorrhage

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Diagnostic investigations for anti-GBM disease?

Anti-GBM antibodies
Normal complement levels 
RENAL BIOPSY
 - LM - crescent formation in bowmans space 
 - IF - continuous IgG staining along BM

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What are the clinical features of PSGN?

Preceding strep infection

1-2 weeks post pharyngitis
3-6 weeks post skin infection

ACUTE NEPHRITIC SYNDROME
Generalised peripheral oedema 
Macroscopic (microscopic) haematuria 
Hypertension
Oliguria

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What investigations would indicate PSGN?

Haematuria with casts + dysmorphic cells
Proteinuria
LOW C3, LOW CH50
Evidence of strep infection - ASOT, anti-DNAse

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What are the indications for a renal biopsy?

Persistently low C3 > 6 weeks
Persistant Proteinuria > 6 months
Atypical presentation
eg. Nephrotic syndrome, deteriorating RF

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What would be the biopsy findings of PSGN?

Only needed in atypical cases

Diffuse proliferation of mesangium and endothelium

IF- C3 + IgG deposits along GBM

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What are the basic management principles of PSGN?

Antibiotic therapy
Fluid restriction 400ml/m2/day
Consider furosemide
Manage severe hypertension

Clinical features of IgA Nephropathy?

Usually >5 years old
Episodic macroscopic Haematuria commonly 1-2 days post URTI
Persistant microscopic haematuria
Loin pain 
Mild hypertension may be present

What are the diagnostic investigations for IgA Nephropathy?

Biopsy - mesangial proliferation with deposits of IgA on IF

Normal renal function
Normal C3 levels

What are the differences between IgA Nephropathy and PSGN?

Haematuria develops 1-2 days post URTI (vs 1-2 weeks)
Resolves within 5 days
Normal C3 levels

What are the clinical features of HSP?

Purpuric rash- buttocks + extensors
Arthritis
Abdominal pain - intussusception rarely
Scrotal pain/tenderness

Haematuria +/- Proteinuria
Hypertension
AKI

What is the management of HSP?

Mostly supportive
NSAIDs for arthritis (avoid if renal disease present)
Corticosteroids for severe abdominal pain/renal disease

Close follow up - BP and urinalysis
Relapses are common

What is the genetic background of Alports syndrome?

Genetic mutations cause dysfunctional coding for Type 4 Collagen X-Linked transmission most common - COL45 gene mutation Can be AD/AR

What are the clinical features of Alports Syndrome?

Persistant microscopic haematuria Progressive Proteinuria BILATERAL SENSORINEURAL HEARING LOSS - never congenital, develops late childhood ANTERIOR LENTICONUS (‘oil drop’ on red reflex) Family hx of deafness and renal failure

What would be seen on a renal biopsy of Alports Syndrome?

Diffuse BM thinning + splitting ‘Basket weave’ appearance of BM IF - Absence of BM staining for alpha-5 collagen (males only)

What are the clinical features of Nephritic Syndrome?

Haematuria Proteinuria Peripheral oedema Hypertension

Hereditary causes of Nephritic syndrome?

Alports syndrome Thin BM disease

What are the causes of Rapidly Progressive GN?

Anti-GBM disease HUS SLE Nephritis Granulomatosis with Polyangiitis

What are the causes of low C3 levels?

Immune complex mediated disease! Post-Strep GN Membranoproliferative GN SLE Nephritis (low C3 + C4)

What are the cardinal features of Nephrotic Syndrome?

Generalised Oedema Proteinuria >4g/24hrs or PCR>2 Hypoalbuminaemia

What is the basic pathogenesis of Nephrotic syndrome?

Primarily podocyte damage leading to increased permeability of capillary walls Both immune and non-immune insults cause: effacement of podocytes Reduced number of functional podocytes and altered integrity of slit diaphragm

What are the primary causes of Nephrotic syndrome?

Minimal Change Disease Membranous Nephropathy Focal Segmental Glomerulosclerosis Congenital Nephrotic syndrome Secondary causes are vasculitis (SLE, HSP) and medications (pamidronate, NSAIDs)

What are the presenting features of nephrotic syndrome?

``` More commonly males Microscopic haematuria Proteinuria ++ AKI (2ndry to hypovolaemia) Oedema ++ ```

What are the complications of Nephrotic Syndrome?

1. Increased susceptibility to infection - urinary loss of Ig + complement - esp encapsulated bacteria (S Pneumonia) 2. Thrombosis 3. Hypovolaemia

What are the basic management principles of Nephrotic Syndrome?

Steroid Therapy Antibiotics Rx severe hypovolaemia - 20% albumin Rx of oedema - fluid restriction, salt restriction Can consider diuretics if no hypovolaemia

What are the volume differences between Nephrotic + Nephritic syndromes?

Nephrotic - low/normal BP, hypovolaemic Nephritic - hypertension, hypervolaemic

What are the clinical features of minimal change disease?

Mild periorbital oedema Proteinuria Occasionally microscopic haematuria - no casts or dysmorphic cells

What are the investigations for MCD?

``` Urine PCR > 300 or significant Proteinuria May be AKI Albumin < 25 Normal complement levels Increased cholesterol ``` Renal biopsy not usually needed

Findings on renal biopsy for MCD?

Normal glomeruli Podocyte Effacement on Electron Microscopy No staining on IF

What is the management of MCD?

``` STEROIDS - Pred for 4 weeks - May relapse after steroid withdrawal Vaccinations - full pneumococcal + flu Antibiotics - initial illness + relapses Manage oedema - Albumin vs. fluid restriction ```

What are the indications for renal biopsy in suspected MCD?

``` <1yr or >16 yrs Steroid resistance Low C3 levels Persisting impaired renal function Persistant microscopic haematuria Hypertension ```

What are the findings seen on renal biopsy for FSGS?

Focal segmental sclerosis Mesangial cell proliferation + scarring IF- IgM + C3 staining in areas of sclerosis

What features in a child with Nephrotic syndrome suggest possible FSGS?

Steroid resistance Adolescents Signs of peristant AKI or hypertension

What is the management of FSGS?

Trial treatment with steroids (only 20% are responsive) | Cyclophosphamide

Membranous Nephropathy is commonly due to an underlying condition, what conditions cause this?

SLE Chronic infections eg. Hep B/C Congenital syphilis