The early changes in retinol-binding protein and prealbumin concentrations in plasma of protein–energy malnourished children after treatment with retinol and an improved diet

Abstract

I . Changes in total retinol-binding protein (RBP), the holoprotein (holoRBP) and prealbumin (PA) concentrations have been monitored in plasma of thirty protein-and vitamin A-deficient preschool children from within a few hours up to 7 weeks after treatment with retinol and a good-quality protein diet.2. The children were classified into groups according to nutritional status as having either kwashiorkor, marasmus-kwashiorkor or marasmus, and given formula diets whose protein and energy contents increased stepwise from I g and 105 kJ/kg body-weight respectively up to 4 g and 733 kJ/kg body-weight after 4 weeks. Retinol was administered in the forms of retinyl palmitate either orally or intramuscularly.3. PA and total RBP were determined by electroimmunoassay procedures and the holoRBP by its fluorescence after separation from other plasma proteins.4. RBP in plasma of the vitamin A-deficient child is largely denatured and incapable of binding administered retinol, which must first be taken up by the liver before native holoRBP is released. An increased pool of native apoprotein accumulates in the liver during vitamin A deficiency which is released into plasma quickly after retinol uptake to form peak concentrations of total and holoRBP approximately 3 h after dosing intramuscularly and 6 h orally.5. The accumulated pool of RBP was highest in livers from the marasmus group and lowest in those from the kwashiorkor group, reflecting their relative capacities to synthesize plasma proteins.6. The mean plasma concentrations of total and holoRBP for the various groups were minimal 24-48 h after dosing with retinol and then improved almost linearly over the following week.7. Mean plasma PA concentrations of the various groups on admission were also in order of the severity of their malnutrition. There was little or no change in this protein concentration over the first 24 h after dosing with retinol, but thereafter the mean values rose almost linearly over 2 weeks. Albumin on the other hand changed little during the first week. The results show that PA is the more sensitive measurement of protein nutritional status.A number of studies have shown that the plasma concentrations of retinol and its carrier, retinol-binding protein (RBP) and prealbumin (PA) are reduced in protein-energy mal- After treatment with a massive dose of retinol and a better-quality protein diet the concentrations of the various components of the vitamin A transport system recovered to levels within the normal range after 1-2 weeks. None of these studies, however, examined plasma RBP concentration within a few hours after dosing with retinol.(The nomenclature used in this paper for the various forms of retinol-binding protein is as follows : retinol-binding protein (RBP) is total immunoreactive protein ; retinol-binding holoprotein (holoRBP) is native protein with its ligand retinol attached ; retinol-binding

Combined Impairment of Nutritional Parameters and Thyroid Homeostasis in Mildly Iodine-Deficient Children

“…may increase rather than decrease RBP levels; however, previous studies showed that the RBP levels and molar ratio with both TTR and retinol are not affected by hypothyroidism (21). Vitamin A deficiency may also reduce the levels of RBP in the blood (23); however, in our patients, the levels of retinol were normal. Therefore, the reduced RBP levels in our patients indeed depend on malnutrition.…”

Serum Retinol-binding Protein 4 is Elevated and Positively Associated with Insulin Resistance in Postmenopausal Women

“…Since many years it has been demonstrated that alterations of retinol intake and vitamin A status affect hepatic release of RbP4 and circulating RBP4 [39][40][41]. A study in the vitamin A-deficient child reported that RbP4 accumulated in the liver during vitamin A deficiency which is released into plasma quickly after retinol uptake to form peak concentrations of total and holo-RbP approximately 3 h after dosing intramuscularly and 6 h orally [42]. Recently, RbP4 was found to be expressed and secreted by adipose tissue, however, RbP4 regulation by vitamin A in the adipose tissue has scarcely been studied.…”

Significance of Plasma Retinol Binding Protein Levels in Recurrence of Breast Tumors in Women

“…Secretion of RBP from the liver is strongly con trolled by the availability of vitamin A in the liver [24][25][26]. Thus, the lower RBP levels in group 2 patients reflect a diminished secretion of this protein from hepatocytes [27], Cycloheximide, puromycin and actinomycin are known to reduce general protein syn thesis [27].…”