One of a group of simple proteins widely distributed in animals and plants. Albumin is found in such substances as blood, milk, and egg whites. In humans it has special relevance to people with diabetes because its presence in urine is a marker of diabetic kidney disease.
The job of the kidneys is to filter protein by-products and water from the bloodstream and to maintain the proper balance of sodium and potassium in the blood. Albumin in the blood has many functions, including the maintenance of a proper balance of fluids between the blood and other tissues. In an early stage of diabetic kidney disease, the kidneys begin removing too much albumin from the blood, and very small amounts of albumin begin to show up in the urine, a condition known as microalbuminuria. Normally, a person has less than 25 milligrams of albumin in their urine each day. A person with microalbuminuria has 30 to 300 milligrams. Microalbuminuria in not uncommon in people who have had diabetes for five years or more.
There is a specific laboratory test to check for microalbuminuria. (The usual urine dipstick tests for protein are not sensitive enough for this purpose.) If the test is positive, measures can be taken — including lowering blood pressure and tightening blood glucose control — to slow or prevent the development of more serious stages of the disease.