What is the classification of Proteinuria

There are tiny pores on normal Glomerular Filtration Membrane, which can stop large molecular weight of protein in blood plasma filtering into urine. Only a bit protein left in glomerular filtration fluid about 20-80mg/24h. The composition of Proteinuria can be divided into some types:

1. Albumin, accounts for 1/3 is from plasma protein.

2. Smaller than the albumin molecular weight of protein, such as light chain of myohemoglobin, β2-microglobulin, immune globulin and small amount enzymes comes from blood, such as Lysozyme, Amylase, Lactic Dehydrogenase, etc.

3. Tissue proteins, which is secreted by Urinary System.
When Urinary Protein is over 150mg/24h, we call it Proteinuria. According to the origin of Urine Protein and formative mechanism of Proteinuria, Proteinuria can be divided into six kinds:

First, is Glomerular Proteinuria: because of damaged Glomerular Filtration Membrane, increased sizes of apertures, or due to reduction and vanish of negative charges on glomerular capillary wall, filtration barrier loses the function of static barrier. Plasma protein, especially large amount of Albumins enter Bowman's capsule, which exceeds reabsorption function from proximal tubule to protein and forms Proteinuria, it is called Glomerular Proteinuria. The feature gives priority to rising Albumin, which accounts for above 70% with normal or tiny increased β2-microglobulin; when Glomerular Filtration Barrier is severely damaged with expanding and increasing filter membrane gap, large molecular weight protein, such as excretion of Immunoglobulin G will also increase.

Tubular Proteinuria: because of kidney tubules damage caused by kidney tubules inflammation and poisoning, micro-molecular protein of Glomerular filtration can not be fully absorbed by kidney tubules and form Proteinuria, which is called Tubular Proteinuria. Protein in urine gives priority to increasing of β2-microglobulin, Lysozyme and other micro-molecular protein. Normal or tiny increased albumin. Discharge rate of Urine Protein everyday is generally less than 1g.

Histic Proteinuria: during the course of urine formation, protein which caused by kidney tubules metabolism as well as damage and degradation of nephridial tissue, and the excretion by stimulation of inflammation or medicine to urinary system go into terminal urine, this kind of urine called Histic Proteinuria. Its protein test usually appears +-/+ with urinary protein is 0.15--1.0g/24h.

Overflow Proteinuria: functions of glomerular filtration and tubular reabsorption are normal, but because increasing of unusual protein in blood, these micro-molecular protein can be filtered through glomerulus, with increasing of spillage, kidney tubules can not absorb these protein, so Proteinuria occurs, which is called Overflow Proteinuria. Its protein test usually appears+--++, light chain and Bence-Jones protein can be examined from urine, or it contains hemosiderin and appears positive reaction.

Mixed Proteinuria: both Glomerulus and kidney tubules are all damaged, small and medium molecular weight protein in urine are all increase.

False Proteinuria: Urinary Tract disease of kidney can cause large amount of pus, blood, mucus and other substances which contain protein, Urine Protein may appear positive, it is called False Proteinuria.