The kidneys work as the filter to remove the extra toxins and other waste products out of the body through the glomerular filtration membrane. Under the normal circumstances, the small molecular proteins pass through the membrane, and 98 percent of which would be absorbed by the renal tubules into the body. The rest proteins together with other proteins secreted by renal tubules and urethra epithelial cells would expel out of body along with the urine. So, only micro proteins exist in the urine of the healthy people.
Under the normal circumstances, the 24-hour urine of the healthy adults includes approximately 40mg-80mg of the protein, no more than 150mg at most. As for the teenager, the 24-hour urine should be less than 300mg. Since the amount of the proteins in the urine is very small, in the clinical, the normal urine is usually defined as negative. If the amount of the protein in the urine exceeds 150mg within 24 hours, it indicates that the glomerular filtration system is destroyed.
Due to the loss of considerable protein, insufficient protein is supplied for liver compounding and degrading, which easily results in hyperlipemia that is the cause of coronary heart disease and myocardial infarction. Besides, as the leaking of the protein into the urine, the amount of the protein in the blood sharply drops, which could cause hypoproteinemia, also called protein malnutrition. In the early time, the patients with this symptom would have puffiness on their faces, and then spreading on the arms and legs. And the fluid may build up in the chest or the abdominal cavity.
