Albumin is a protein made by the liver and is the most abundant protein in blood. It helps keep fluid from leaking out of blood vessels and carries substances such as hormones, vitamins, and medications through the bloodstream. This test measures the amount of albumin in the blood. This test is used to help assess overall nutrition status and to evaluate how well the liver and kidneys are working. It is often part of routine health panels and can help identify problems related to liver disease, kidney disease, or malnutrition.