Prealbumin (transthyretin) is a transport protein produced by the liver that carries thyroid hormones and serves as a sensitive marker of nutritional status and liver function. This test measures prealbumin levels in the blood to evaluate protein malnutrition, monitor nutritional therapy, and assess liver dysfunction. Prealbumin has a short half-life of only 2-3 days, making it more responsive to changes in nutritional status than albumin. Low prealbumin levels can indicate protein malnutrition, inflammatory conditions, liver disease, or protein-wasting disorders of the gut or kidney. Elevated levels may occur in Hodgkin's disease or certain inflammatory conditions. This test is particularly valuable for monitoring patients on total parenteral nutrition, evaluating response to nutritional interventions, and assessing protein status in hospitalized patients or those with chronic diseases.