Figure 4

Extracellular and intracellular compartments in children with dehydration. Normally the extracellular compartment makes up approximately 20 percent and the intracellular 40 percent of the body weight (upper panel of the figure). The second, third and fourth panels depict the relationship between extracellular and intracellular compartment in three children with dehydration in the context of an acute diarrheal disease: dehydration is normotonic-normonatremic in the first, hypotonic-hyponatremic (mainly extracellular fluid losses) in the second, and hypernatremic (mainly intracellular fluid losses) in the third child. The lower panel depicts the relationship between extracellular and intracellular compartment (mainly intracellular fluid losses) in a child with dehydration in the context of diabetic ketoacidosis (hypertonic-"normonatremic" dehydration; in this context the concentration of circulating sodium is normal or even reduced). In each panel the solid circles denote sodium and open circles impermeable solutes that do not move freely across cell membranes (in the present example glucose). For reasons of simplicity, no symbols are given for potassium, the main intracellular cation.