Hormonal Control of Weight Gain in Infants Recovering from Protein Energy Malnutrition. I. The Effect of Insulin and Metabolic Rate

Abstract

SpeculationDuring recovery from protein energy malnutrition, the augmented insulin release and metabolic rate that occurs with increased energy intake induces rapid rates of weight gain.During recovery from protein energy malnutrition the rate of weight gain and the energy intake are closely related (1,2, 25,30,36). The rate of weight gain is also positively correlated with metabolic rate (3,7,30). However, the relationship of both rate of weight gain and metabolic rate to the output of plasma insulin has not been reported.In malnutrition insulin output is low after intravenous glucose (4, 5, 20, 27), glucagon (27), and arginine (14) and there is a poor insulin release after a protein-glucose meal in untreated marasmic and marasmic-kwashiorkor infants (1 5). These responses improve after partial rehabilitation (4,5,15, 20, 27). Whether or not abnormally low insulin release characteristic of protein energy malnutrition (PEM) persists after clinical recovery remains in doubt (5,12,20,24,27). Most studies so far have compared insulin status in malnourished and clinically recovered children, and little attention has been paid to the intermediate phases of recovery where rate of weight gain may be 10 or 15 times the normal. This phase of extremely rapid weight gain has been termed "catch up growth."In this study, therefore, the authors compared plasma insulin, metabolic rate, and other metabolic variables during the phase of rapid weight gain with those shown during malnutrition and aAer clinical recovery, using a physiologic stimulus-a high energy test meal. EXPERIMENTAL PROCEDUREInformed parental consent was obtained for all studies. Professional peer review and approval of the proposed investigation was obtained. An initial study was done on eight of the children when malnourished (M) and on maintenance diet. No initial study was done on the others because they were either febrile or had vomiting, diarrhea, or specific infection. Thirty-one studies were done in 15 children during the period of rapid weight gain (R) and seven studies were done in seven clinically recovered children (C). Those children who passed the expected weight for their height and continued to gain weight rapidly were included in the recovering group (R). All studies were conducted in the early afternoon after a 4-hr fast. One hr before the study, a slow iv infusion of saline was set up in order to obtain serial blood samples without disturbing the child and oral paraldehyde (0.5 ml/kg body weight) was administered via a nasogastric tube. A 4-hr fasting metabolic rate was estimated from oxygen consumption and carbondioxide production using a Kipp and Zonen Noyons diaferometer. The instrument was calibrated by combusting known amounts of alcohol in the hood for the child. Observations of respiratory exchange made for 5 successive min were averaged and the results for each interval combined. A blood sample was withdrawn immediately before the test meal (Table 2) was given by nasogastric tube. The meal provided 174 joules and 0.9 g protein/kg body...