Regulation of metabolism of retinol-binding protein by vitamin A status in children with biliary atresia

Regulation of retinol-binding protein (RBP) by vitamin A status was studied in 43 children; 25 had biliary atresia and vitamin A deficiency, 15 had biliary atresia treated by vitamin A, and 9 control children had normal liver and vitamin A status. Vitamin A and RBP were assayed and the two forms of RBP, holo-RBP and apo-RBP, were separated in both liver and plasma. No difference in liver RBP concentrations was found between the three groups; apo-RBP was the most abundant form. Plasma RBP concentrations and the ratio of retinol to RBP were lower for vitamin A-deficient than for vitamin A-treated children. Two models could be proposed: 1) a preferential secretion of holo-RBP with variations in RBP catabolism or synthesis in vitamin A-deficient liver and 2) a continuous secretion of RBP by the liver with a rapid clearance of plasma apo-RBP in vitamin A deficiency.