What is the Difference Between Prealbumin and Albumin?

Prealbumin and albumin are both proteins produced in the liver, but they have different functions and half-lives, which affect their usefulness in assessing nutritional status. Here are the main differences between prealbumin and albumin:

1. Half-life: Prealbumin, also known as transthyretin, has a half-life of 2 to 4 days, while albumin has a half-life of 20 to 22 days.
2. Function: Prealbumin is a transport protein for thyroid hormone and is synthesized by the liver. It is also partly catabolized by the liver. Albumin, on the other hand, is responsible for maintaining the blood's osmotic pressure and transporting various substances.
3. Nutritional assessment: Prealbumin is often preferred over albumin due to its shorter half-life, which allows it to reflect more rapid changes in nutritional status. Albumin levels are an indicator of long-standing nutritional deficiencies and rise slowly once the deficiency is addressed.
4. Sensitivity to comorbidities: Prealbumin levels are not impacted by comorbidities or hydration status, but can be impacted by corticosteroids and Hodgkin's disease. Albumin levels, however, can be influenced by various conditions, such as hemoconcentration (dehydration), heart failure, or kidney disease.

In summary, prealbumin and albumin are both used to assess nutritional status, but prealbumin is more sensitive to short-term changes due to its shorter half-life. However, it is essential to consider the influence of various comorbidities and hydration status when interpreting these protein levels.

Comparative Table: Prealbumin vs Albumin

Here is a table comparing the differences between prealbumin and albumin:

Prealbumin, also known as transthyretin, is a transport protein for thyroid hormone and retinol, while albumin is a transport protein in the serum that helps move many small molecules through the blood. Prealbumin has a shorter half-life than albumin, making it a more sensitive indicator of protein status and more useful for assessing acute changes in nutritional status. Albumin, on the other hand, is an indicator of long-standing nutritional deficiencies and rises slowly once the deficiency is corrected.