Fluid and electrolytes in the aged.

OBJECTIVE: To review the physiological changes in fluid and electrolytes that occur in aging. DATA SOURCES: Data collected for this review were identified from a MEDLINE database search of the English-language literature. The indexing terms were fluids, intravenous fluids, fluid resuscitation, fluid management, perioperative, electrolytes, aged, elderly, hemodynamics, hyponatremia, hypernatremia, hypocalcemia, hypercalcemia, hypomagnesemia, hypermagnesemia, hypophosphatemia, hypokalemia, and hyperkalemia. Relevant references from articles obtained by means of the above search terms were also used. STUDY SELECTION: All pertinent studies were included. Only articles that were case presentations or did not specifically address the topic were excluded. DATA SYNTHESIS: The fastest-growing segment of the population in the United States is individuals 65 years or older. It is imperative that health care professionals review the physiological changes that manifest during the aging process. Fluids and electrolytes are important perioperative factors that undergo age-related changes. These changes include impaired thirst perception; decreased glomerular filtration rate; alterations in hormone levels, including antidiuretic hormone, atrial natriuretic peptide, and aldosterone; decreased urinary concentrating ability; and limitations in excretion of water, sodium, potassium, and acid.
CONCLUSIONS: There are age-related alterations in the homeostatic mechanisms used to maintain electrolyte and water balance. Health care providers must familiarize themselves with these alterations to guide treatment of this growing population.