Why Is There A Lot of Proteinuria For Nephrotic Syndrome

As we all know, proteinuria is a very common symptom of nephrotic syndrome, but how many people are there know the reason why lots of proteinuria exists.
Water and solute in blood enter renal capsule via glomerulus to become initial urine, this process must through the endothelial cells , basement membrane of capillary wall and epithelial cells. These three layer structures are called the glomerular filtration membrane. All of the three filtration membranes have certain holes, which only allows the materials that have certain molecular weight and molecular diameter to pass, so they are the size barrier of filtration membranes. The surfaces of three layer structures are covered by silaoprotein, and glomerular basement membrane inside and outside loose layer have rich heparan sulfate, these substances take negative charge in fluid environment, so they reject the solutes that take negative charge to pass, then the charge barrier of filtration membranes forms.

In addition, the intraglomerular mesangium which lies among glomerular capillaries has a regulating action to filtration barrier of glomerulus, so also has a certain effect to the filtration of glomerulus. Under the normal circumstances, most of the protein in blood can not go through the filtration barrier of glomerulus, especially the macromolecules and the albumins that take negative charge almost completely can not go through, a small amount of small molecule proteins which had gotten through filtration can be reabsorbed by kidney tubules, so protein expelled from urine is less than 150mg.

At the time of nephrotic syndrome, barrier function of filtration membrane is destroyed by a variety of pathogenic factors, the holes become bigger and negative charge decreases, which leads to the leakage of a large amount of protein, it outdistance the ability of reabsorption of kidney tubules, so a great quantity of proteinuria appears.

For nephrotic syndrome patients, they also have hypoalbuminemia because of the loss of lots of protein. So they should arrange their diet reasonably and find a good method to solve this problem from the origin.