Albumin is a major protein in the human body, making up about 60% of total human plasma protein by mass. Many hormones, drugs, and other molecules are mostly bound to albumin in the bloodstream and must be released before becoming biologically active.
Albumin is synthesized in the liver, and low serum albumin may be indicative of liver failure or diseases such as cirrhosis or chronic hepatitis. Hypoalbuminemia can also present as part of the nephrotic syndrome, in which protein is lost in the urine due to kidney damage. Low albumin levels can be an indicator of chronic malnutrition.
Hypoalbuminemia may cause generalized edema (swelling) via a decrease in oncotic pressure.
The serum albumin level is part of a standard panel of liver function tests. Levels below 3.5 grams per deciliter are generally considered low.