What is the function of albumin in the bloodstream?

• A. Clotting
• B. Immune defense
• C. Maintain fluid within vessels
• D. Transport of oxygen

Answer: (C)

Albumin’s job in the bloodstream is to keep fluid inside the vessels by maintaining oncotic (colloid osmotic) pressure. As a large plasma protein produced by the liver, albumin helps draw water from the surrounding tissue back into capillaries, helping to preserve intravascular volume and prevent edema. While it also serves as a carrier for various substances, its essential role related to fluid balance is sustaining this intravascular fluid, which is why it’s described as maintaining fluid within vessels. In contrast, clotting involves platelets and clotting factors, immune defense involves antibodies, and oxygen transport is primarily the job of hemoglobin. That makes maintaining fluid within vessels the best description of albumin’s function in the bloodstream.