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Proteinuria is a medical term used to describe high levels of protein in the urine. Under normal conditions, people do not have protein in their urine because structures in the kidneys known as glomeruli filter out proteins so that they can be reused by the body. In people with this condition, the protein indicates that there is a medical problem which needs to be addressed.
The cause of proteinuria is kidney damage which interferes with the function of the glomeruli, so that they cannot filter out protein. Glomerulonephritis, in which these structures become inflamed, is a common cause. Proteinuria is also associated with cardiovascular problems, including high blood pressure, and diabetes, all of which can put strain on the kidneys so that they cannot function normally. Protein in the urine can also be caused by infections and inflammations of the urinary tract.
Some people develop edema, especially in their hands and feet. The swelling of the hands and feet may be uncomfortable, and it can mean that shoes and rings will not fit as they normally would. Foamy urine, caused by a change in surface tension, can also develop in people with high levels of protein in their urine. Other individuals develop no symptoms, only discovering the problem during a medical exam.
This condition is diagnosed by taking a urine sample from a patient and analyzing it. Many labs have a simple “dipstick test” in which a strip coated in protein-sensitive material is dipped into the urine to check for the presence of protein. It is also possible to analyze the urine chemically. Albumin is the protein most commonly present in patients with this condition, although other proteins can be present as well.
Proteinuria is simply a symptom of an underlying medical condition. By treating the cause, the excess protein in the urine will usually be resolved as well. Because kidney problems can lead to very serious medical issues, the presence of excess protein in the urine is a cause for concern and it should be addressed by a doctor.
In athletes, proteinuria sometimes develops after exercise, and it may be revealed on drug testing or routine physical examinations. Originally, doctors thought that this was a sign of kidney damage, but subsequent studies have suggested that this is actually normal, especially for young athletes. If the athlete rests in a reclining position and then repeats the test, the protein levels should drop back to normal.