INTRACELLULAR COMPOSITION AND HOMEOSTATIC MECHANISMS IN SEVERE CHRONIC INFANTILE MALNUTRITION

Abstract

The present report deals with preliminary results on the study of renal function in advanced malnutrition. The glomerular filtration rate (clearance of inulin) and renal plasma flow (clearance of para-aminohippurate) were studied in 10 children with severe chronic malnutrition. Osmolar clearance were also measured in six of these children. In three, with marked hypotonicity despite acute dehydration, the effects of intravenous administration of a load of sodium chloride were studied. A significant reduction in filtration rate and renal plasma flow was encountered, which was most evident during dehydration. A decrease in osmolar clearance and the presence of "free-water" clearance in both non-dehydrated and dehydrated malnourished children suggested suspension of the usual antidiuretic mechanisms for conservation of water; however, the rise in osmolar clearance and reabsorption of osmotically free water following administration of hypertonic saline, indicated that the capacity of the renal tubules to respond to an adequate stimulus was not lost. Administration of an hypertonic solution of saline produced a marked expansion of the volume of extracellular fluid. More than half of this expanded volume resulted from redistribution of intracellular "endogenous" water. Expansion of volume limited rise of osmolality of extracellular fluid in two cases, but failed to do so in the third. A relatively large proportion of the filtered water was excreted during hypotonic dehydration. Filtration rates apparently decreased as the proportion of filtered water excreted became increased. The possibility that reduction in filtration rate constitutes a volume defense mechanism and that the apparent anomalies in renal function represent an adaptation to the cellular hypotonicity of the malnourished subject are discussed.