Proteinuria is a typical symptom of kidney disease, but the amount of urine protein leakage does not reflect the severity of kidney disease. Leakage of urinary protein in patients with mild chronic kidney disease does not necessarily mean that the pathological damage of the kidney is light; a large amount of proteinuria does not indicate that the pathological damage of nephropathy is serious. Such as minimally pathological nephritis and mild mesangial proliferative nephritis, kidney disease is mild, but the daily urine protein can reach several grams or even dozens of grams. According to the degree of filtration membrane damage and the composition of urine protein, urine protein is divided into two categories:
(1) Selective proteinuria: mainly between 4 and 90,000 relative molecular masses of albumin, which may be associated with proteins with similar molecular mass such as antithrombin, transferrin, glycoprotein, etc. and a small amount of small relative molecular mass. β2-M, Fc fragment and the like. There are no proteins with high molecular weight (IgG, IgA, IgM, C3, etc.). The immunoglobulin/albumin clearance rate is less than 0.1, the urine protein is 3+~4+, and the quantitative is more than 3.5g/24h, which is common in nephrotic syndrome.
(2) Non-selective proteinuria: reflecting severe rupture and damage of the glomerular capillary wall. Urine protein is mainly composed of relatively high molecular weight and medium protein, such as IgM, IgG and complement C3, albumin, glycoprotein (TH glycoprotein), secretory IgA (SIgA) and a small amount of mucin protein secreted by the lower urinary tract. Wait. The immunoglobulin/albumin clearance rate is greater than 0.5, and the urine protein is qualitatively 1+ to 4+, with a dose of 0.5 to 3.0 g/24 h. Non-selective proteinuria is a persistent proteinuria that develops a risk of renal failure and often suggests a poor prognosis.