Metabolism, Fluid Distribution, and Renal Function

Abstract

Abstract Pediatric physiology differs keenly from adult physiology in a number of ways. This chapter looks at differences in metabolism, fluid distribution, and renal function. Neonates and acutely ill children are more vulnerable to depletion of glycogen stores. Metabolism of medications is often prolonged in neonates due to fewer active enzymes; is more rapid in children; and reaches adult values in adolescence. Infants have a higher body water percentage by weight than adults do. Infants also have more fluid in the extracellular compartment, including the intravascular space, compared to adults. Renal filtration function and urine-concentrating ability in neonates are much less developed than in adults, leading to prolonged clearance rates of renally excreted drugs. Similarly, neonates are also more vulnerable to fluid perturbations and electrolyte imbalances until their homeostatic autoregulatory mechanisms more fully develop.