What are the components of Oral Rehydration Solution (ORS) for pediatric use?

Components of Oral Rehydration Solution (ORS) for Pediatric Use

Standard ORS contains four essential components: sodium chloride (3.5 g/L), trisodium citrate dihydrate (2.9 g/L), potassium chloride (1.5 g/L), and glucose (20 g/L), dissolved in 1 liter of clean water. 1

Core Electrolyte and Glucose Composition

The fundamental components work synergistically to enable optimal intestinal absorption:

• Sodium chloride (3.5 g/L) provides the primary electrolyte for sodium-glucose cotransport mechanism 1
• Trisodium citrate dihydrate (2.9 g/L) replaces bicarbonate as the base, offering longer shelf life with equivalent efficacy 2
• Potassium chloride (1.5 g/L) replaces potassium losses from diarrhea 1
• Glucose (20 g/L or 111 mmol/L) drives the sodium-glucose cotransport system that enables water absorption 3

Sodium Concentration Guidelines by Clinical Indication

The American Academy of Pediatrics provides clear differentiation based on clinical scenario:

For Active Rehydration

• Use 75-90 mEq/L sodium concentration when treating established dehydration 2, 4
• Mandatory for high purging rates (>10 mL/kg/hour) to match severe electrolyte losses 2, 5
• WHO-ORS with 90 mmol/L sodium represents the gold standard for rehydration across all etiologies, ages, and nutritional states 3

For Maintenance and Prevention

• Use 40-60 mEq/L sodium concentration after rehydration is complete 2, 4
• Lower sodium solutions better approximate stool losses in viral diarrhea common in developed countries 2
• When using solutions >60 mEq/L for maintenance, supplement with low-sodium fluids (breast milk, formula, or water) to prevent sodium overload 2, 4

Osmolarity Specifications

• Total osmolarity should be 311 mOsm/L for standard WHO-ORS 3
• Low-osmolarity formulations (240-270 mOsm/L) may reduce stool output but require validation 6
• Excessive glucose or carbohydrate concentration creates osmotic diarrhea by drawing water into the gut lumen 2

Common Commercial Formulations in the United States

• Pedialyte: 45 mEq/L sodium - designed for maintenance, not validated for rehydration 2
• Ricelyte: 50 mEq/L sodium with 30 g/L rice-syrup solids - successfully used for both rehydration and maintenance 2
• These lower-sodium products can substitute for higher-sodium solutions when the alternative is IV therapy or inappropriate fluids 2

Alternative Carbohydrate Sources

Beyond standard glucose-based ORS:

• Rice-based ORS uses cooked rice powder providing complex carbohydrate polymers that avoid excessive osmotic load 2
• Rice polymers are slowly digested to glucose, potentially reducing stool output in first 6 hours 2
• Other substrates evaluated include sucrose, glycine, alanine, and glutamine, though glycine-based formulations risk hypernatremia 2

Critical Pitfalls to Avoid

• Never add significant amounts of juice to ORS - even small additions of apple or orange juice decrease sodium by 30-53 mmol/L and increase osmolarity above therapeutic range 7
• Do not use sports drinks, soft drinks, or apple juice alone - these have inappropriate electrolyte composition for rehydration 8
• Avoid excessive carbohydrate concentration (>2.5% glucose) combined with high sodium, which promotes hypernatremia 3
• Watch for hypernatremia risk factors: abundant watery diarrhea, well-nourished infants <6 months, and concurrent solute loads 3
• Do not flavor ORS at home - use commercially flavored products that maintain proper electrolyte composition 7

Preparation and Storage Considerations

• Pre-mixed solutions ensure accurate concentration and eliminate mixing errors 8
• Packet formulations require precise measurement - provide detailed written and oral instructions when dispensing 2
• Citrate-based formulations have replaced bicarbonate for improved shelf life without compromising efficacy 2