Summary

Glomerulonephritis (GN) is inflammation of the glomeruli, the filtration units of the kidney. It classically presents as Nephritic Syndrome:

1. Haematuria (Dysmorphic red cells and RBC casts).
2. Hypertension (Volume overload).
3. Oliguria / AKI (Reduced GFR).
4. Proteinuria (Mild/Moderate less than 3g/day). It ranges from benign (Post-Strep GN) to life-threatening (Anti-GBM Disease). Early recognition prevents irreversible End Stage Renal Failure (ESRF). [1,2]

Clinical Pearls

Synpharyngitic vs Post-Infectious: The key history differentiator for a young male with haematuria.

• IgA Nephropathy: Haematuria occurs 1-2 days after the sore throat (Synpharyngitic).
• Post-Strep GN: Haematuria occurs 2 weeks after the sore throat (Post-infectious).

Pulmonary-Renal Syndrome: Any patient with AKI and Haemoptysis has Goodpasture's (Anti-GBM) or Vasculitis (GPA) until proven otherwise. This is a medical emergency requiring urgent immunology and often Plasma Exchange.

Red Cell Casts: The pathognomonic finding on urine microscopy. These are red blood cells that have been squeezed through the inflamed glomerular basement membrane and cemented together by Tamm-Horsfall protein in the tubules. They prove the bleeding is glomerular (not bladder/ureteric).

Low Complement (C3/C4)

(Suggests immune complex consumption)

1. Post-Infectious (Post-Strep): Follows Group A Strep. Anti-Streptolysin O (ASO) positive.
2. Lupus Nephritis (SLE): ANA / dsDNA positive.
3. Cryoglobulinaemia: Associated with Hepatitis C.

Normal Complement

1. IgA Nephropathy (Berger's): High serum IgA.
2. ANCA Vasculitis:
   • GPA (Wegener's): cANCA (PR3). Systemic symptoms (Sinusitis, Epistaxis, Lungs).
   • MPA: pANCA (MPO). Kidney limited usually.
3. Anti-GBM Disease: Anti-GBM positive. Pulmonary hemorrhage.

• Post-Strep: Excellent (95% recovery in kids).
• IgA: Variable. "Rule of Thirds" (1/3 resolve, 1/3 stable, 1/3 progress to failure).
• Vasculitis: Good remission rates but high relapse risk.
• Anti-GBM: Poor renal recovery if dialysis-dependent at presentation.

Key Guidelines

Landmark Evidence

1. RAVE Trial (NEJM 2010)

• Proved Rituximab was non-inferior to Cyclophosphamide for ANCA vasculitis induction, and superior for relapsing disease. Changed the standard of care.

What is Glomerulonephritis?

The kidneys are full of millions of tiny sieve-like filters called glomeruli. Your immune system has made a mistake and attacker these filters, causing them to become inflamed and swollen.

Symptoms?

Because the filters are damaged, blood leaks into the urine (making it look like smoky tea or cola). The kidneys also stop filtering water out properly, so you swell up (puffy eyes/ankles) and your blood pressure goes up.

Is it dangerous?

It can be. Some types (like after a throat infection in kids) act like a mild allergic reaction and go away on their own. Others (like Vasculitis) are more aggressive and can permanently scar the kidneys if we don't use strong medicines to dampen the immune system.

The Biopsy

To know which type you have and how strong the medicines need to be, we usually need to take a tiny sample of the kidney using a needle.

Common Exam Questions

1. Diagnosis: "Haematuria 2 days after sore throat?"
   • Answer: IgA Nephropathy.
2. Diagnosis: "Haematuria + Haemoptysis?"
   • Answer: Goodpasture's (Anti-GBM) or GPA.
3. Pathology: "Crescents on biopsy?"
   • Answer: Rapidly Progressive GN (RPGN).
4. Immunology: "cANCA positive?"
   • Answer: Granulomatosis with Polyangiitis (Wegener's).

Viva Points

• Complement levels: Why are they low in Post-Strep/Lupus? Because the immune complexes consume the complement factors.
• Goodpasture vs Wegener's: Both cause Pulmonary-Renal syndrome. Goodpasture's has Anti-GBM antibodies (linear IF). Wegener's has cANCA (pauci-immune IF) and usually has nasal/sinus symptoms too.

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.