Albumin is a protein manufactured by the liver.
Liver disease, kidney disease, and malnutrition are the major causes of low albumin. A diseased liver produces insufficient albumin. In malnutrition there is not enough protein in the patient's diet for the liver to make new albumin from. The normal value depends on the laboratory running the test. Most labs consider roughly 3.5 to 5 grams per deciliter to be normal.