is a condition where the urine contains an abnormal amount of proteins. Albumin is the main protein in the blood. Proteins are the building blocks for all body parts, including muscles, bones, hair, and nails. Proteins in the blood also perform a number of important functions. They protect the body from infection, help blood clot, and keep the right amount of fluid circulating throughout the body.

As blood passes through healthy kidneys, the waste products are filtered out and proteins that the body needs, like albumin and other proteins, are kept. Most proteins are too big to pass through the kidneys' filters into the urine. However, proteins from the blood can leak into the urine when the filters of the kidney, called glomeruli, are damaged.

Proteinuria is a sign of chronic kidney disease (CKD), which can result from diabetes, high blood pressure, and diseases that cause inflammation in the kidneys. If CKD progresses, it can lead to end-stage renal disease (ESRD), when the kidneys fail completely. An individual with ESRD must receive a kidney transplant or regular blood-cleansing treatments called dialysis.