Block 4: glomerulonephritis and RRT Flashcards
Anti-GBM autoantibodies= cause of nephritic syndrome
- An immune-mediated pathology involving antibodies directed against glomerular basement membrane antigens (anti-GBM antibodies)
- Investigations: Immunohistochemistry (IgG deposits along the basement membrane of the glomerulus), Antibodies (anti-GBM antibodies)
- Management: high dose immunosuppression (IV prednisolone, cyclophosphamide and plasmapheris)
- The antigens are located in the glomeruli and in the alveoli of the lungs causing nephritic syndrome and alveolar haemorrhage presenting as haemoptysis. If both lungs and kidneys are involved its Goodpastures
Nephrotic syndrome
Triad of:
- Heavy proteinuria >3.5g/day
- Hypoalbuminaemia (<35 g/L)
- Peripheral oedema
- May be accompanied by Hyperlipidaemia and thrombotic disease
- Can develop AKI but less common then in nephritic
Non-proliferative (structural) nephrotic syndrome
Glomerular damage characterised by structural changes and often sclerosis (scarring of the glomeruli). May show diffuse scarring or only subtle changes under electron microscope. Typically associated with excess protein loss and nephrotic syndrome.
Causes of nephrotic syndrome
- Primary: due to renal glomeruli injury. Minimal change disease, Focal segmental glomerulosclerosis, Membranous nephropathy
- Secondary: Glomeruli injury due to wider systemic injury. For example diabetes mellitus, Amyloidosis, HIV
Nephrotic syndrome: investigations
- Gold standard: renal biopsy
- Urine: dipstick (detects albumin), Urine protein:creatinine ratio (normal is <30mg/mmol), 24 hour urinary collection (urine is collected over 24 hours to determine the protein content. Normal is <0.2g)
- Blood tests: FBC, U&E’s, bone profile, HbA1c, blood gas, lipid profile (hyperlipidaemia in nephrotic syndrome)
- Imaging: renal ultrasound or CT KUB
Symptoms of nephrotic syndrome
- Fatigue
- Poor appetite
- Peripheral oedema, Periorbital oedema: less protein so loss of oncotic pressure and increased movement of fluid into the interstitial space
- Shortness of breath: typically from pleural effusions and/or
pulmonary oedema - Foamy urine: due to excess protein loss
- Signs: ascites, effusion (dull percussion note and reduced air entry)
Complications of nephrotic syndrome
- Thrombotic: both arterial and venous, causes DVT and PE
- Hyperlipidaemia: fall in oncotic pressure increases lipoprotein synthesis causing higher levels of cholesterol. Reduced triglyceride metabolism due to reduced activity of lipoprotein lipase
- Recurrent infections: due to loss of immunoglobulins through glomeruli
- AKI
Minimal change disease
- Cause of nephrotic syndrome- majority of cases in young children
- Mostly idiopathic but can be due to Drugs (NSAID’s), malignancy (lymphoproliferative disorders), infections (syphilis).
- Due to fusion of podocyte processes causing immune dysfunction and disruption of the filtration barrier
- In children assume minimal change and start treatment, in adults need renal biopsy
- Management: systemic glucocorticoids (prednisolone). Second line is further courses of prednisolone or more intensive immunosuppresants
Glomerulonephritis cause: Focal segmental glomerulosclerosis
- Causes of nephrotic syndrome- common cause in adults
- Refers to sclerosis in parts of at least one glomerulus
- Primary FSGS: due to a circulating factor that damages podocytes causing them to spread out, reducing the effectiveness of the filtration barrier
- Secondary FSGS: an adaptive response to renal injury, causes less proteinuria and renal impairment. Causes glomerular hypertrophy and hyperfiltration. Causes: severe obesity, reflux nephropathy and reduction in kidney mass
- Diagnosis: renal biopsy
- Management: primary FSGS is treated with immunosuppressive medication and steroids. Secondary FSGS is about treating the underlying cause i.e. weight loss in obesity
Membranous nephropathy
- Most common cause of nephrotic syndrome in adults
- Glomerular basement membrane thickening without significant cellular proliferation
- Primary MN: an autoimmune reaction against antigens in the filtration barrier. Development of autoantibodies, formation of immune deposits and thickening of glomerular basement membrane. Primarily antibodies against phospholipase A2 receptor (PLA2R)
- Secondary: due to underlying infection, drug use or systemic disorder i.e. SLE, viral hepatitis, prostate cancer, NSAID’s
- Management: some have spontaneous remission. If high risk but no irreversible damage then use immunosuppressive agents in primary. In secondary target underlying cause
Renal amyloidosis
- Cause of nephrotic syndrome- extracellular deposition of fibrils that contain proteins
- There are two systemic forms: AL amyloidosis (excess light chains due to
plasma cell disorders) and AA amyloidosis (excess precursor protein due to chronic inflammation). - Amyoid fibrils contain insoluble proteins that form beta pleated sheets that are resistant to degradation and deposit in organs- some are genetic
- Diagnosis: renal biopsy with identification of amyloid fibrils using Congo red staining, can sample tissue from another site as its systemic
- Management: depends on cause i.e. AA amyloidosis, hereditary amyloidosis. In renal involvement supportive management is needed. In end stage dialysis may be used
Renal screen nephrotic syndrome
- Complement: typically low in vasculitis
- Anti-nuclear antibody (ANA)
- Anti-neutrophil cytoplasmic antibody (ANCA)
- Anti-glomerular basement membrane antibody (GBM)
- Anti-dsDNA: raised in systemic lupus erythematosus
- Myeloma screen: serum free lights chains, protein electrophoresis
- Anti-PLA2R autoantibody: raised in membranous nephropathy
- Virology: Hepatitis B, Hepatitis C and Human immunodeficiency virus
- Cryoglobulins: immunoglobulins that precipitate at low temperatures
- Creatine kinase: may be raised in rhabdomyolysis
Management in glomerular disease
- Regular monitoring
- Treat underlying causes: corticosteroids in minimal change disease and immunosuppressors in ANCA associated vasculitis
- Treat complications: i.e. nephrotic syndrome causes hyperlipidaemia and nephritic syndrome has extra-renal manifestations i.e. pulmonary haemorrhage
- Consider renal replacement therapy
Renal replacement therapy definition
Term used to encompass life supporting treatment for renal failure. Includes all types of dialysis and kidney transplantation
Dialysis techniques
- Continuous hemofiltration
- Continuous haemodialysis
- Peritoneal dialysis
- Intermittent haemodialysis
Dialysis time scale
Can be intermittent or continuous. Continuous therapy is used in an AKI when it has benefits over intermittent therapy due to improved tolerability due to slower removal of solute and water
Haemodialysis
- Blood comes into contact with a semi-permeable membrane (in the dialyser) which contains dialysate on the other side, substances diffuse across
- Works as an artifical kidney
- The solutes are removed with the dialysate
- Can be performed in hospital or at home. In hospital its 4 hours 3 times a week
- Require either an arteriovenous fistula (takes around 6-8 weeks to become usable after formation) or a tunnelled central venous catheter
- Arteriovenous fistula: Preferred dur to more complications with lines (particularly infection)
AV fistula
Small surgery allows blood to be diverted from an artery to a vein, high pressure arteriole blood causes the vein to enlarge and thicken. So, two large bore needles can be inserted regularly. Provides better quality dialysis
Complications of Haemodialysis
- Access-related: infection (including bacteraemia leading to endocarditis, discitis), venous stenosis, access failure
- Haemodynamic instability
- Nausea and vomiting
- headache
- cramps, particularly leg cramps
- Reactions to dialysis membranes
Peritoneal dialysis
- The vascularised peritoneum acts as the dialysis membrane
- Dialysis fluid in the peritoneal cavity creates osmotic gradients causing water removal (ultrafiltration), convection and diffusion of solutes across the membrane
- After several hours the used fluid is drained out and fresh fluid is installed
- Just as effective as haemodialysis and is performed for 8-12 hours a day, usually overnight and in their own home
- The dilatate contains varying amounts of glucose which creates a high osmotic pressure helping to draw out extra fluid from the body that the patient doesn’t require