Prealbumin and albumin are both proteins but differ in their structure, function, and biological roles. Prealbumin, also known as transthyretin (TTR), is a protein synthesized in the liver and primarily involved in transporting thyroid hormones and vitamin A. Albumin, on the other hand, is the most abundant protein in the blood and serves various functions, including maintaining oncotic pressure, transporting substances, regulating pH balance, and providing amino acids for tissue repair. While both proteins can indicate nutritional status, Prealbumin has a shorter half-life and may respond more rapidly to changes in protein intake or metabolism compared to albumin.