albumin:

a protein found in blood plasma and urine, which can be a sign of kidney disease. 

The most abundant protein component of blood, Produced primarily in the liver, albumin helps to keep the fluid portion of blood within the vessels, and helps transport drugs and other substances by way of the bloodstream. Low levels of albumin in the blood or its presence in urine may signal edema (the accumulation of fluid) as in pedal edema (in the ankles) or pulmonary edema (in the lungs), which may be symptoms of congestive heart failure, kidney or liver disease. 

One of a simple group of water soluble blood proteins. In the blood, albumin acts as a carrier and helps to maintain blood volume and blood pressure. A blood test for albumin helps to determine if a patient has kidney disease or if the body is not absorbing enough protein.