Renal (Glomerulonephritis) Flashcards
Nephritis and glomerulonephritis
Nephritis describes damage to the kidneys due to inflammation.
Glomerulonephritis describes nephritis involving the glomerulus.
structure of the glomerulus
Ultrafiltration occurs at the glomerulus. Liquid and small molecules need to pass through 3 layers to enter the nephron tubules:
1) The capillary endothelium:
- Allows fluid, plasma proteins, and large substances through
- Does not allow red or white blood cells and some proteins through
2) The glomerular basement membrane:
- Allows fluid and solutes through
- Does not allow intermediate-large substances including some proteins through
3) The epithelium of the Bowman’s capsule (made of podocytes):
- Allows fluid and small solutes through
- Does not allow large molecules such as proteins through
These three layers filter the blood with each layer preventing increasingly large substances from passing through into the nephron tubule. Overall, cells (such as red blood cells or white blood cells) and large proteins are not passed through.
nephritic vs nephrotic sydrome : location of disorder
1) Nephritic syndrome describes the signs and symptoms generally seen due to dysfunction of the capillary endothelium. This usually refers to severe and acute presentations of glomerulonephritis.
2) Nephrotic syndrome describes the signs and symptoms generally seen due to the dysfunction of podocytes. It is less associated with inflammation.
summary of nephritis vs nephrotic syndrome
Nephrotic syndrome
Active urine sediments with or without renal insufficiency, with nephrotic range proteinuria (>3g in 24hrs)
- Diabetes
- Minimal changes disease
- Membranous
- FSGS (focal segmental glomerular sclerosis)
amyloid
Nephritic syndrome
Active urine sediments with or without renal insufficiency, with mild proteinuria – blood in urine
- IgA nephropathy
- Lupus
- Mesangial proliferative glomerulonephritis
- Vasculitis
Nephrotic syndrome overview
Damage and dysfunction of the podocytes can lead to a loss of protein in the urine. As mentioned above, the podocytes are the ‘last line’ of filtration where large molecules such as proteins are prevented from entering the nephron tubule. Nephrotic syndrome is defined as:
- Proteinuria (>3.5 g/24hr)
- Hypoalbuminaemia
- Oedema
Other features that may also be seen include:
- Hyperlipidaemia
- Hypercoagulability
- Immunodeficiency
presentation of nephrotic syndrome
- Swollen e.g. periorbital and oedema
- Proteinuria >3 g in 24s hours
- Low serum albumin
- Hyperlipidaemia
- Hypercoagulable state
cause of nephrotic syndrome
In children
- 90% minimal change disease
In adults
- Minimal change
- Membranous nephropathy
- Focal segmental glomerulosclerosis (35%)
- Membranoproliferative glomerulonephritis
- Amyloid
Pathophysiology of minimal change
Where podocyte become effaced -> losing the ability to control the amount of protein leaked into the urine
management of nephrotic syndrome
Oedema
- Diuretics, need large doses and may need to be I.v. if gut oedema
- Salt and fluid retention
ACE-i
- Anti-proteinuria but caution if intravascularly deplete or if renal function deteriorating acutely
Hypercholesterolaemia
- Atherogenic if long-term nephrotic
- Life style advice and statins
Treat underlying condition
- Steroids for Minimal change disorder, underlying cause of disease
Diabetic nephropathy (DN)
describes a chronic reduction in kidney function associated with diabetes mellitus. It is characterised by proteinuria and a progressive reduction in the estimated glomerular filtration rate (eGFR). It generally occurs around 5-10 years after the onset of diabetes mellitus and can lead to chronic kidney disease (CKD).
screening for diabetic nephropathy
Since the predominant feature in DN is proteinuria, and many patients may be asymptomatic, all patients with both type 1 or type 2 diabetes mellitus should be screened annually with a urinary albumin:creatinine ratio (ACR). An ACR ≥3 mg/mmol is considered clinically significant.
management of diabetic nephropathy
- Optimise control of diabetes mellitus
- If ACR ≥3 mg/mmol: ACE inhibitor or angiotensin-II receptor blocker (ARB): slows progression
- If ACR ≥30 mg/mmol: ACE inhibitor/ARB and offer dapagliflozin if relevant eGFR thresholds are met
- Consider adding dapagliflozin to ACE inhibitor/ARB if ACR between 3-30 mg/mmol and relevant eGFR thresholds are met
Minimal change disease (MCD)
is the most common form of nephrotic syndrome in children. Its exact pathogenesis is unclear and immunofluorescence and light microscopy testing on biopsies showed no or minimal changes, hence MCD’s name. However, with electron microscopy, a diffuse loss of podocytes is seen, explaining proteinuria and the development of nephrotic syndrome.