Oral Rehydration

Description

• Oral rehydration therapy (ORT) is a clinically useful, cost-effective, and safe technique to treat mild and moderate dehydration.
• ORT is as effective as IV hydration and the treatment of choice for mild to moderate dehydration.
• ORT can be divided into rehydration and maintenance phases.
• ORT should have an osmolality of ~245 mOsm/kg, a sodium (Na⁺) content of ~75 mEq/L, and a glucose concentration of ~75 mmol/L (13.5 g/L).
• Fruit juices, soda, popsicles, sports drinks, and broth often have inappropriate Na⁺ and/or electrolyte concentrations for isolated ORT.
• Although ORT can be prepared at home, commercially prepared solutions eliminate potential recipe errors.
• System(s) affected: endocrine/metabolic, gastrointestinal

Epidemiology

Incidence

• In 1980, diarrheal illness contributed to 4 to 6 million deaths annually in children age <5 years. By 2018, this declined to fewer than 500,000 annual deaths (despite a 70% increase in the world’s population).
• Acute diarrheal illness remains the second leading cause of mortality in children age <5 years in developing countries.
• Exercise-related dehydration is common (1).

Etiology and Pathophysiology

ORT takes advantage of the preserved coupled transport of Na⁺ and glucose in the small intestine during infectious gastroenteritis and exercise-associated dehydration. Water follows Na⁺ osmotically. Potassium is passively absorbed via solvent drag. An equimolar concentration of glucose and Na⁺ is most effective for ORT.

• Fluids with a higher ratio of glucose (juice, soda, sports drinks, etc.) have a high unabsorbed glucose load, which increases osmolality in the lumen, decreases water absorption, and increases diarrheal losses.
• Fluids with higher ratio of Na⁺ (chicken broth, etc.) lack enough solute for transport of Na⁺, leading to increased diarrheal losses (and potentially hypernatremia).