According to WHO guidelines for rehydration therapy in acute diarrhea, what is the recommended osmolarity of oral rehydration solution (ORS)?

Explanation

## WHO Low-Osmolarity ORS Composition **Key Point:** The WHO and UNICEF recommend low-osmolarity ORS (245 mOsm/L) as the gold standard for treating acute diarrhea in children. This formulation reduces stool output and the need for supplemental intravenous therapy compared to standard ORS. ### Composition of WHO Low-Osmolarity ORS | Component | Concentration (mmol/L) | |-----------|------------------------| | **Sodium chloride** | 75 | | **Potassium chloride** | 20 | | **Glucose (anhydrous)** | 75 | | **Trisodium citrate dihydrate** | 10 | | **Total osmolarity** | **245 mOsm/L** | **High-Yield:** The 1:1 sodium-to-glucose molar ratio (75:75 mmol/L) is critical because it optimizes coupled transport via the sodium-glucose cotransporter (SGLT1) in the small intestine, maximizing water and electrolyte absorption. ### Advantages of Low-Osmolarity ORS 1. **Reduced stool output** — approximately 20% decrease compared to standard ORS 2. **Lower incidence of hypernatremia** — less risk of osmotic diarrhea 3. **Decreased need for IV therapy** — fewer children require supplemental rehydration 4. **Improved absorption** — optimal glucose-sodium ratio enhances intestinal uptake **Mnemonic:** **LOWS** = **L**ow-osmolarity, **O**ptimal glucose-sodium ratio, **W**ater absorption enhanced, **S**tool output reduced **Clinical Pearl:** Standard ORS (311 mOsm/L) is now considered suboptimal and is rarely recommended. Low-osmolarity ORS is preferred in all age groups for acute diarrhea, including cholera.