Thyroxine-binding prealbumin (TBPA) appears as a sensitive blood parameter for assessing various forms of protein and calorie malnutrition, ranging for subclinical protein deficit to frank kwashiorkor. More precisely, TBPA serves as a valid marker for determining both protein nutritional adequacy and the optimal ratio of energy and zinc to nitrogen intake in healthy newborns and preterm infants without infection. When inflammation is present, the decrease in TBPA blood levels reflects a deterioration in the patient's condition and its increase monitors the efficacy of dietary management. In this latter inflammatory context, it is recommended to combine the measurement of TBPA with that of the most reliable indicators of the phlogistic reaction, allowing the discrimination of both infectious and nutritional poles of the disease spectrum.