Repletion of the plasma pool of nutrient transport proteins occurs at different rates during the nutritional rehabilitation of severely malnourished children.

Increased morbidity and mortality are associated with lower plasma protein concentrations in children with severe protein-energy malnutrition. However, the kinetic changes responsible for repletion of the plasma pools of nutrient transport proteins and the rapidity of their replenishment in these children have not been determined. This study was undertaken to determine whether an increased rate of synthesis is the mechanism responsible for repletion of the plasma retinol-binding protein, transthyretin and high density lipoprotein-apolipoprotein A1 concentrations of children with severe malnutrition during nutritional rehabilitation. The plasma concentrations and synthesis rates of retinol-binding protein, transthyretin and high density lipoprotein-apolipoprotein A1 were measured using a constant intragastric infusion of 2H3-leucine in 22 children with severe protein-energy malnutrition, at approximately 2 d postadmission (study 1), approximately 8 d post-admission when infections were under control (study 2) and approximately 59 d postadmission at recovery (study 3). In study 1 the plasma concentrations and rates of synthesis of all the proteins were lower compared with values at recovery. In study 2, retinol-binding protein and transthyretin concentrations and absolute synthesis rates increased to the recovered values seen in study 3, but the high density lipoprotein-apolipoprotein A1 concentration and synthesis rate remained significantly lower. These results suggest that repletion of the plasma pool of these three nutrient transport proteins occurs at different rates, through an increase in the rate of synthesis.