More Information Introduction Proteinuria describes a condition in which urine contains an abnormal amount of protein.
Proteins are the building blocks for all body parts, including muscles, bones, hair, and nails.
As blood passes through healthy kidneys, they filter the waste products out and leave in the things the body needs, like proteins. Most proteins are too big to pass through the kidneys' filters into the urine, unless the kidneys are damaged. The two proteins that are most likely to appear in urine are albumin and globulin. Albumin is smaller and therefore more likely to escape through the filters of the kidney, called glomeruli. Albumin's function in the body includes retention of fluid in the blood.