Which of the following is not present in the WHO Oral Rehydration Solution (ORS)?

Appeared in: RML 2023

Explanation

Magnesium Sulphate is not a standard component of the World Health Organization (WHO) recommended Oral Rehydration Solution (ORS).
The WHO ORS formula is specifically designed with components that are essential for correcting dehydration and electrolyte imbalances caused by diarrhea.
Adding other substances like Magnesium Sulphate could alter the solution's osmolarity and effectiveness, and potentially worsen diarrhea due to its laxative properties.

Option A: Trisodium citrate is a key component of WHO ORS. It is included to correct metabolic acidosis that often accompanies severe diarrhea.
Option B: Sodium chloride (table salt) is a fundamental ingredient in WHO ORS, essential for replacing lost sodium and chloride ions.
Option D: Glucose is crucial in the WHO ORS formula. It facilitates the absorption of sodium and water in the small intestine via the SGLT1 co-transporter, making rehydration more efficient.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Composition of WHO Oral Rehydration Solution (ORS) as background academic context rather than a clinical decision trigger.
ORS is a cornerstone of managing acute diarrhea, especially in children, and has dramatically reduced mortality from diarrheal diseases worldwide.
Nurses must educate caregivers on the correct preparation of ORS: one packet must be mixed in exactly 1 liter of clean water. Using too little water makes the solution hypertonic and can worsen diarrhea, while too much water dilutes the electrolytes, making it less effective.
What if a patient with diarrhea also has severe vomiting? If the patient vomits, the nurse should advise waiting for 10 minutes and then resuming ORS administration more slowly, in small, frequent sips. If vomiting persists and prevents oral rehydration, the patient may require intravenous fluids and medical evaluation.

How to Approach the Question

First, identify the core of the question. It asks you to find the substance that is not part of the standard WHO ORS.
This is a negative-framing question, requiring you to know the correct components to identify the incorrect one.
Recall the four main ingredients of the low-osmolarity WHO ORS: Sodium Chloride, Potassium Chloride, Glucose, and Trisodium Citrate.
Systematically compare each option against your recalled knowledge.
Trisodium Citrate is a component. Eliminate Option A.
Sodium Chloride is a component. Eliminate Option B.

Concept Tested & Keywords

Concept Tested: Composition of WHO Oral Rehydration Solution (ORS)
Stem keywords: WHO, Oral Rehydration Solution, ORS
Lead-in keywords: not present
Negative lead-in flag: The question asks to identify the component that is NOT present in WHO ORS.

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Practise the full RML 2023

Attempt every question from this paper in a timed mock, then review the full solution for each one.