Pediatrics
Diarrhoeal Diseases and Dehydration
Paediatric diarrhoea and dehydration for NEET-PG: ORS composition, WHO Plan A/B/C, zinc, IMNCI classification and dysentery, mapped to NMC PE24 codes.
MedNext Academy | 3 min read
Diarrhoeal Diseases and Dehydration
Paediatric diarrhoea and dehydration for NEET-PG: ORS composition, WHO Plan A/B/C, zinc, IMNCI classification and dysentery, mapped to NMC PE24 codes.
This chapter covers acute, persistent and chronic diarrhoea in children with the physiology and practice of oral rehydration therapy, WHO and IMNCI classification of dehydration, and the fluid, zinc and feeding pillars of management. It includes the emergency-access skills used in severe dehydration.
High-yield: Diarrhoeal Diseases and Dehydration
- Classify diarrhoea first by duration and by the presence of blood, then classify dehydration by clinical signs, and most management questions become straightforward.
- The low-osmolarity oral rehydration solution contains sodium 75, glucose 75, potassium 20, citrate 10 and chloride 65 mmol/L with a total osmolarity of 245 mOsm/L.
- Ringer lactate and normal saline are resuscitation fluids, while oral rehydration solution is the definitive fluid for most mild to moderate diarrhoeal dehydration.
- For some dehydration, give oral rehydration solution 75 mL/kg over four hours (WHO Plan B), and for severe dehydration use Plan C with rapid isotonic intravenous fluid.
- Zinc supplementation, given as elemental zinc about 1 mg/kg/day for 10 to 14 days per local formulations, is part of standard diarrhoea management alongside continued feeding.
- Antibiotics are indicated for dysentery, cholera with severe dehydration, likely protozoal disease, sepsis and high-risk hosts, not for routine watery diarrhoea.
- Shigella is the default paediatric dysentery organism for examinations; amoebiasis is not the commonest explanation in young children.
- Loperamide or diphenoxylate in a febrile, toxic, bloody or young child is dangerous because it can worsen ileus and invasive infection.
- The four classic IMNCI dehydration signs are general condition, sunken eyes, drinking behaviour and skin pinch, and three questions are asked in every case: duration, blood and dehydration.
- Diarrhoea usually causes hypokalaemia and a hyperchloraemic metabolic acidosis, while sodium may be low, normal or high depending on losses and replacement fluids.
- Hypernatraemic dehydration can look deceptively less dehydrated because extracellular volume is partly preserved, with neurological irritability and doughy skin as warning clues.
- Potassium replacement before the child passes urine is unsafe, because renal perfusion and urine output decide the timing of potassium correction.
- A hanging drop preparation supports cholera by showing darting motility in fresh stool, but culture confirms the organism and guides public-health action.
- Persistent diarrhoea lasts at least 14 days and is often a nutritional emergency disguised as a stool complaint, so the growth chart matters as much as the stool report.
- Bloody diarrhoea with reduced urine, pallor, bruising, hypertension or rising creatinine suggests haemolytic uraemic syndrome until proven otherwise.
Low-osmolarity ORS composition
- **Sodium and potassium:** Sodium 75 mmol/L and potassium 20 mmol/L.
- **Glucose and chloride:** Glucose 75 mmol/L and chloride 65 mmol/L.
- **Citrate and osmolarity:** Citrate 10 mmol/L with a total osmolarity of 245 mOsm/L.
- **WHO Plan B volume:** Oral rehydration solution 75 mL/kg over four hours for some dehydration.
NMC competencies in this chapter
- **PE24.1:** Diarrhoeal Diseases: Etiopathogenesis, Classification, Presentation and Management
- **PE24.3:** Physiological Basis of Oral Rehydration Therapy and ORS Composition
- **PE24.8:** Dysentery in Children
- **PE24.11:** Applying IMNCI Risk Stratification and Referral in Diarrhoeal Dehydration
- **PE24.14:** Planning Fluid Management as per WHO Criteria
Frequently Asked Questions
What is the composition of low-osmolarity ORS?
It contains sodium 75, glucose 75, potassium 20, citrate 10 and chloride 65 mmol/L, giving a total osmolarity of 245 mOsm/L. This is the definitive fluid for most mild to moderate diarrhoeal dehydration.
How much ORS is given for some dehydration under WHO Plan B?
Oral rehydration solution is given at 75 mL/kg over four hours and the child is then reassessed. Severe dehydration is managed with Plan C using rapid isotonic intravenous fluid.
When are antibiotics indicated in childhood diarrhoea?
Antibiotics are reserved for dysentery, cholera with severe dehydration, likely or proven protozoal disease, sepsis and high-risk hosts. Routine watery diarrhoea is not an indication, and antidiarrhoeal drugs like loperamide are dangerous in young, febrile or bloody cases.
Why can hypernatraemic dehydration be dangerous to assess?
It can look deceptively less dehydrated because extracellular volume is partly preserved. Neurological irritability and doughy skin are warning clues, and sodium must be corrected slowly to avoid cerebral oedema.
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