Albumin: Bountiful Arrow in the Quiver of Liver and Its Significance in Physiology

Albumin is the most abundant protein synthesized exclusively by the hepatocytes in the liver. Once secreted into plasma, it helps in the maintenance of osmotic pressure, as well as the exertion of defensive roles such as anti-oxidative and anti-inflammatory functions. Dysregulation in the synthesis and clearance of albumin is observed in various hepatic and extra-hepatic diseases. Abnormal levels of albumin could be either a cause or an effect of various pathological ailments, including hepatic, cardiac, renal, neurological, etc. Owing to its long half-life and multiple binding sites in its heart-shaped structure, it interacts with various internal agents, such as hormones, or external substances like drugs, which is why transportation can be one of its many functions. Additionally, albumin’s drug interactions, as well as displacement of albumin–drug binding, could have serious clinical consequences, and careful considerations should be made in determining an appropriate drug regimen to achieve a desired therapeutic outcome with minimal side effects. Moreover, albumin also undergoes several post-translational modifications that can influence its physiological roles, including drug binding and antioxidant functions. Furthermore, it has a complicated role in physiology, where it can help in maintaining plasma oncotic pressure and prevent endothelial cell apoptosis but can have adverse effects on the lungs and kidneys. These adverse effects are mainly attributed to ER stress and inflammasome activation. This narrative review provides an overview of the general biology of albumin and its effects in physiology, with a focus on its beneficial and adverse effects and the underlying molecular mechanisms.