How can glomerulonephritis cause both proteinuria/hematuria and uremia?
The glomeruli of the kidneys are the parts that normally filter the blood. They consist of capillaries that are fenestrated (leaky, due to little holes called fenestrae or windows) and that allow fluid, salts, and other small solutes to flow through, but normally not proteins. In nephrotic syndrome, the glomeruli become damaged due to inflammation and hyalinisation (membrane formation) so that small proteins, such as albumins, immunoglobulins and anti-thrombin can pass through the kidneys into urine. Albumin is the major protein in the blood which maintains colloid osmotic pressure- this prevents leakage of blood from vessels into tissue. However, experiments show that the edema formation in nephrotic syndrome is more so due to microvascular damage and intense salt and water retention by the damaged kidneys (due to increased angiotensin secretion). The mechanism is very complex and still not fully understood. Uremia is the build up of urea, the metabolic by-product of protein metabolis
