Proteinuria and Kidney Diseases

Proteinuria is closely related with the kidneys and it is the typical symptom of chronic kidney diseases. Proteinuria means more than normal protein leakage in urine (more than 150mg). Though it has much to do with the renal glomerular filtration ability and renal tubular re-absorption ability, not all proteinuria case is caused by kidney diseases.

Here are the types of proteinuria according to different causes.

Glomerular proteinuria

It is the most common type of proteinuria and caused by damages of the glomerular filtration membrane due to inflammation, immune and metabolic disorders, etc. Glomerular proteinuria can be further divided into selective proteinuria and non-selective proteinuria according to the severity of the renal damages and components of urinary proteins. Selective proteinuria is often found in nephrotic syndrome and non-selective proteinuria is more common in primary and secondary glomerular diseases. Non-selective proteinuria is persistent and will often develop into renal failure if not treated timely and properly.

Tubular proteinuria

It is protein leakage in urine caused by damages of tubular re-absorption ability due to infections, toxicity or glomerular diseases. Urinary protein in this type are mainly small molecular.

Mixed proteinuria

It has the feature of both the above mentioned two types of proteinuria. Renal damages in this type involve both the glomeruli and tubules.

Overflow proteinuria

In this type of proteinuria, the glomerular filtration and tubular re-absorption are all normal. Excessive protein in urine is caused by abnormal increase of small molecular proteins or proteins of positive charge. It is often found in multiple myeloma.

Histic proteinuria

This kind of proteinuria comes from tubular metabolism, tissue damages, and inflammation or medicine stimulation to the urinary tract system.

From the above analysis, we can see that most proteinuria cases are caused by kidney damages. In a word, there are many types of proteinuria according to the location of renal damages---glomerular proteinuria, tubular proteinuria, mixed proteinuria, overflow proteinuria, histic proteinuria and also false proteinuria. Accordingly different medicines and treatment plans will be required according different types of proteinuria and the severity of renal damages.