Nephritic Syndrome
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Nephritic Syndrome is a clinical presentation of Glomerulonephritis (GN), characterized by proliferation of cells within the glomeruli causing inflammation.
It is defined by the classic pentad:
- Haematuria (Macroscopic or Microscopic).
- Hypertension.
- Oliguria (Reduced urine output).
- Mild Oedema (Periorbital/Legs).
- Proteinuria (Usually < 3.5g/day - termed "sub-nephrotic").
Clinical Scenario: The Smoky Urine
A 24-year-old man presents with 'coca-cola coloured' urine. He has a sore throat that started yesterday. BP is 150/95.
Key Teaching Points
- **Diagnosis**: Likely **IgA Nephropathy** (Berger's Disease).
- **Clue**: 'Synpharyngitic' Haematuria (occurs *simultaneously* with the sore throat).
- **Differentiation**: **Post-Streptococcal GN** occurs 1-2 weeks *after* the infection.
- **Investigation**: Urine microscopy will show **Red Cell Casts** (confirming glomerular origin).
Image Integration Plan
| Image Type | Source | Status |
|---|---|---|
| Management Algorithm | AI-generated | PENDING |
| Pathophysiology (Crescent) | AI-generated | PENDING |
| Urine Micro (RBC Casts) | Web Source | PENDING |
| IgA Immunofluorescence | Web Source | PENDING |
[!NOTE] Image Generation Status: Diagrams illustrating the Glomerular Inflammation vs Protein Leak are queued.
Nephritic vs Nephrotic
| Feature | Nephritic | Nephrotic |
|---|---|---|
| Pathology | Inflammation (Proliferation) | Podocyte Injury (Leak) |
| Urine | Haematuria (RBC Casts) | Proteinuria (>.5g/day) |
| Oedema | Mild (Periorbital) | Severe (Anasarca) |
| BP | High | Normal/Low |
- IgA Nephropathy: Most common GN worldwide. Young Asian males.
- Post-Strep GN: Children (2-10y). Developing countries.
- Goodpasture's: Rare. Young men (lung/kidney phenotype) or Elderly women (kidney only).
- Immune Deposition: Immune complexes (IgA, IgG, C3) deposit in the glomerulus.
- Inflammation: Complement activation attracts neutrophils/macrophages.
- Damage: Proliferation of mesangial/endothelial cells blocks the capillary loops.
- Filtration Failure:
- Low GFR -> Oliguria -> Volume Overload -> Hypertension & Oedema.
- Capillary Rupture -> RBCs leak into tubule -> Haematuria & Casts.
- BP: Mandatory.
- Fluid Status: JVP? Lung crackles? Pedal oedema?
- Skin: Purpuric rash (Henoch-Schonlein Purpura / Vasculitis).
- Urine Dipstick: Blood+++, Protein++.
- Urine Microscopy (Crucial): Red Cell Casts (RBCs glued together by Tamm-Horsfall protein). Acorn-shaped / Dysmorphic RBCs.
- Bloods:
- U&E (Creatinine).
- Immunology Screen:
- C3/C4: Low in Post-Strep, SLE, Cryoglobulinaemia. Normal in IgA.
- ANCA: c-ANCA (PR3) = GPA. p-ANCA (MPO) = Microscopic Polyangiitis.
- Anti-GBM: Goodpasture's.
- ANA/dsDNA: SLE.
- ASOT: Anti-Streptolysin O (Recent Strep).
- Renal Biopsy: Gold Standard for definitive diagnosis.
A. General Measures
- Fluid Restriction: To manage overload.
- Diuretics: Furosemide.
- BP Control: ACE-Inhibitors / CCBs.
- Salt Restriction.
B. Specific Treatment (Biopsy guided)
- IgA Nephropathy:
- Conservative (BP control with ACEi) for most.
- Steroids if rapid deterioration.
- Post-Streptococcal GN:
- Supportive. Usually self-limiting. Antibiotics for residual strep.
- ANCA Vasculitis / SLE:
- High dose Steroids + Cyclophosphamide / Rituximab.
- Anti-GBM Disease:
- Plasma Exchange (Plasmapheresis) to remove antibodies.
- Steroids + Cyclophosphamide.
- RPGN (Rapidly Progressive GN): Crescentic formation. Loss of kidney function in days/weeks. Needs urgent immunosuppression.
- CKD / ESRD: Requiring dialysis.
- Pulmonary Oedema.
- Post-Strep: Excellent (>95% recovery in children).
- IgA: Variable. "Rule of Thirds" (1/3 resolve, 1/3 stable, 1/3 progress to ESRD).
- RPGN: Poor without rapid treatment.
- KDIGO Guidelines (2021): Management of Glomerular Diseases.
What is Nephritic Syndrome? It is a group of symptoms caused by inflammation of the filters (glomeruli) in the kidneys. Think of the kidneys like a sieve. Usually, only water and waste gets through. In Nephritic syndrome, the sieve is "angry" and inflamed. It gets blocked (so you pee less) and it lets blood cells leak through (so your pee looks dark/smoky).
Why is my pee dark? It contains microscopic amounts of blood. Because the urine is acidic, the blood turns brown/tea-coloured rather than bright red.
What caused it?
- Infection: Sometimes it happens after a throat infection (Strep throat) where the immune system gets confused and attacks the kidneys.
- Autoimmune: Conditions like Lupus can cause it.
How do we treat it? We need to control your blood pressure very carefully. We might use steroid tablets to calm the inflammation. In mild cases (like after a throat infection), it often gets better on its own with just rest and blood pressure pills.
- KDIGO. Clinical Practice Guideline for the Management of Glomerular Diseases. 2021.
- Floege J, et al. The pathogenesis and treatment of glomerulonephritis. Lancet. 2016.
- Cattran DC, et al. Kidney Disease: Improving Global Outcomes (KDIGO) Glomerulonephritis Work Group. Kidney Int Suppl. 2012.