Electrolyte requirements are related to fluid metabolism and,
consequently, are similar between adults and children, with allowances for weight
differences.
Sodium is the primary extracellular cation, a major component of the
serum osmolarity and is essential for growth as well as fluid homeostasis.
Maintenance requirements for sodium are from 2-4 mEq/kg/day. Requirements
may be greater for infants due to renal immaturity and the inability to maximally
reabsorb sodium. Sodium requirements may also be affected by the
administration of naturetic agents such as theophylline, caffeine, furosemide and
dopamine. Hyponatremia is most frequently a result of water retention due to
excess antidiuretic hormone secretion. Conversely, hypernatremia is most
frequently due to dehydration.
Potassium is the primary intracellular cation and is essential for proper
cardiac and neurologic function. Daily requirements are 1-2 mEq/kg/day to
account for cellular proliferation and to replace obligatory renal losses.
Consequently, for decreased renal function, careful adjustment and often
cessation of potassium supplementation may be needed. Potassium is most
safely administered by the enteral route; intravenous infusion should generally be
0.5 mEq/kg/hour with no greater than 1 mEq/kg/hr. Potassium is inflammatory to
veins and therefore should be given at concentrations of no more than 60 mEq/L
in peripheral lines and 120 mEq/L in central lines, but usually at lower