Albumin maintains the osmotic pressure that pulls water into the circulatory system. The pressure inside blood vessels exerted by pumping of the heart (hydrostatic pressure) creates a force to push fluids out of veins and arteries into the surrounding tissue. Albumin prevents this by drawing fluids in due to osmosis.
Albumin binds hormones, vitamins, drugs, fatty acids, minerals, and other substances in the blood, carries them throughout the body, and delivers them to body tissues. Albumin has many locations where substances can attach to.
Albumin is also the main antioxidant in blood. It works by binding with metals and reacting with free radicals, which prevents them from reacting with other parts of the body and causing damage