Differential Diagnosis and Management of Fluid, Electrolyte and Acid-Base Disorders

In this chapter, the disturbances of fluid, electrolyte and acid-base balance will be addressed. The first part will discuss water and salt metabolism, with particular attention to body fluid compartments, the role of effective circulating volume and measurement of sodium. This will put the basis for a detailed discussion of dehydration, a frequent problem in pediatrics. Hyponatremia and hypernatremia will be discussed, with respect to their causes, their symptoms and signs, their diagnostic work up and their management. A similar structure will help the discussion of potassium balance, hypo- and hyperkalemia. The second part is dedicated to acide-base balance, which will be addressed in a pathophysiologically-based way, with particular attention to metabolic acidosis and metabolic alkalosis: symptoms and signs, causes, clinical work up and management. Finally, according to the same structure, calcium, magnesium and inorganic phosphate metabolism will be discussed.