Glomerulonephritis

Glomerulonephritis (GN) is inflammation or immune-mediated injury involving the kidney glomeruli. The glomerulus is a filter made of capillaries, and everything that follows comes from what happens when that filter is inflamed. It leaks, because the barrier is damaged, so red blood cells and protein escape into the urine. It also filters less, because the capillaries are swollen and crowded with inflammatory cells. The kidney then holds on to sodium and water, and that retained volume raises blood pressure and produces oedema. The sequence is worth holding as one chain: 1. Immune or inflammatory injury 2. Glomerular capillary inflammation 3. Damage to the filtration barrier 4. Red blood cells and protein enter the urine 5. Reduced filtration and sodium retention 6. Hypertension, oedema and kidney dysfunction GN may therefore cause haematuria, proteinuria, reduced kidney filtration, sodium and water retention, hypertension, oedema, and acute or chronic kidney dysfunction. It may occur as a primary kidney disorder or as part of systemic disease. Several mechanisms can start the chain: - Immune-complex deposition - Complement activation - Autoantibody-mediated injury - Pauci-immune small-vessel vasculitis...