Prealbumine

Prealbumin, more commonly known as transthyretin (TTR), is a small transport protein found in blood plasma and cerebrospinal fluid. It binds and transports thyroxine (T4) and the retinol-binding protein–retinol complex, contributing to the delivery of thyroid hormone and vitamin A. Transthyretin is mainly produced by the liver, with additional synthesis in the choroid plexus, and circulates as a homotetramer of about 55 kDa.

The protein has a relatively short plasma half-life, around two days, which allows it to reflect recent changes in nutrition and inflammation more rapidly than some other markers. Because of this property, prealbumin has been used as a nutritional biomarker in hospital settings to monitor response to nutritional support. However, interpretation is complex: levels are influenced by inflammatory states, liver function, renal loss, hydration status, and certain medications, limiting its specificity as a sole indicator of protein-energy malnutrition.

As a negative acute-phase reactant, prealbumin levels decrease during acute illness and systemic inflammation, sometimes independently of nutritional intake. Conversely, levels can be affected by hepatic disease (reduced production) or nephrotic syndrome (increased loss). Therefore, while helpful for tracking short-term changes, prealbumin should be interpreted in the context of clinical assessment and other laboratory markers, such as C-reactive protein.

Historically, the term prealbumin arose from its migration pattern on electrophoresis, where it moved before albumin. Today it is primarily regarded as transthyretin, with its diagnostic and prognostic value nuanced by its sensitivity to inflammatory and hepatic conditions. See also albumin, retinol-binding protein, and transthyretin-related pathways.