What is the typical sodium concentration range for oral rehydration solutions?

• A. 60-90 mmol/L
• B. 30-60 mmol/L
• C. 90-120 mmol/L
• D. 120-150 mmol/L

Answer: (A)

Sodium in oral rehydration solutions is kept at a level that supports efficient water absorption in the gut without risking high serum sodium. The typical range of 60–90 mmol/L provides enough sodium to replace losses from diarrhea through the sodium–glucose co-transport mechanism, while staying safely below concentrations that could cause hypernatremia or osmotic issues. In practice, many standard ORS formulations are about 75 mmol/L, which falls right in the middle of this range. Lower-than-typical sodium can under-replace losses, while higher concentrations (toward 120 mmol/L or more) increase the risk of adverse effects and poor tolerance.