What is the primary function of albumin in the blood?

Albumin serves a crucial role in maintaining osmotic pressure within the blood. It is a protein synthesized by the liver and is the most abundant plasma protein, comprising about 60% of the total protein in plasma. The primary function of albumin is to ensure that the oncotic pressure—the pressure exerted by proteins in the blood—is sufficient to keep fluid within the vascular compartment, preventing it from leaking into the surrounding tissues.

By maintaining this osmotic balance, albumin helps regulate the distribution of fluids between blood vessels and tissues, which is vital for overall fluid homeostasis. When levels of albumin are low, there can be a shift of fluid into the interstitial space, leading to edema and other complications.

While albumin also plays a role in transporting hormones, fatty acids, and other substances, its primary and most critical function is the regulation of osmotic pressure within the bloodstream. This property is essential for maintaining normal blood volume and pressure, thereby enabling effective circulatory function.