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Plasma vitamin A, retinol-binding protein, and prealbumin concentrations have been studied in 38 northern Thai children with protein-calorie malnutrition (PCM). The 4-week study period consisted of 1 week of stabilization followed by 3 weeks of treatment with formula diets varying in their protein and calorie content. The stabilization period comprised 7 days of initial treatment with fluids, antibiotics, and a gradually increasing intake of protein and calories to a final level of 1 g protein and 100 kcal/kg of body weight. During this period vitamin A, retinol-binding protein and prealbumin levels all showed significant increases compared to admission values, whereas plasma albumin and total protein did not change. During the subsequent 3 weeks, the effects of four different dietary regimens, with daily calorie and protein intakes of 100 or 175 kcal/kg and 1 or 4 g/kg, respectively, were studied. Significant increases in plasma total protein concentration were seen in each of the four test groups, and increases in plasma albumin and prealbumin were also seen in three of the four test groups, and increases in plasma albumin and prealbumin were also seen in three of the four test groups (all but the 175 kcal-1 g protein group). Significant increases in plasma vitamin A levels were not seen in any of the groups. The higher protein regimens (4 g/kg per day) resulted in much greater increases in plasma albumin and total protein levels than did the lower protein regimens. No significant differences in the changes in retinol-binding protein or vitamin A levels were apparent between the test groups. Sixteen additional children with both clinical vitamin A deficiency and protein-calorie malnutrition showed significant increases in total plasma vitamin A concentrations 24 hours after the intramuscular injection of 100,000 IU water-miscible vitamin A palmitate, without a change in plasma retinol-binding protein concentrations. These studies demonstrate that plasma retinol-binding protein and prealbumin concentrations are more rapidly responsive and sensitive to dietary protein intake than is plasma albumin concentration. Furthermore, the absence of a 24-hour rise in plasma retinol-binding protein after parenteral vitamin A provides further evidence that hepatic retinol-binding protein synthesis is impaired in protein-calorie malnutrition.

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

1. alpha 2HS-glycoprotein accumulates in bone and dentine and its plasma levels could vary in conditions in which the rate of bone formation is altered. 2. The plasma concentration of this protein was found to be lower in thirteen children suffering from protein-energy malnutrition compared with age-matched healthy preschool children. 3. This finding might be associated with the phenomenon of stunting in protein-energy malnutrition.