Transthyretin in the Evaluation of Health and Disease in Human and Veterinary Medicine

Transthyretin (also known as prealbumin) is an important transport protein, which plays an essential role in the binding of thyroid hormones and retinol with varying affinities in mammalian, as well as avian species. The determination of transthyretin concentrations may be used as a diagnostic tool for some disease conditions in humans, but is more often used as a nutritional marker to assess protein-calorie malnutrition and as prognostic indicator in critically ill patients. Transthyretin has shorter half-life (2–3 days) than that of albumin and belongs to negative acute phase proteins. This may complicate the use of transthyre- tin as a nutritional marker and the interpretation of results in the diagnosis of diseases. Although some studies have been carried out to determine the usefulness of transthyretin in selected disease conditions and disorders also in animals, it is a relatively rarely used parameter to evaluate health state and illness in veterinary medicine. The usefulness of transthyretin in the diagnosis of diseases and evaluation of nutritional status in humans and animals are reviewed in this article, including the laboratory assays available to mea- sure its concentrations and the possible clinical application of the results, as well as its usefulness as a prognostic indicator in some disease conditions.