← Diagnosis and Management Guides
Pediatric Dehydration
Key considerations: Hypovolemic shock, Diabetic ketoacidosis (DKA), Pyloric stenosis
Cannot miss
- Hypovolemic shock
- Diabetic ketoacidosis (DKA)
- Pyloric stenosis
- Intussusception
- Adrenal crisis
- Inborn error of metabolism
Likely diagnoses
- Viral gastroenteritis (rotavirus, norovirus)
- Acute otitis media with poor intake
- Pharyngitis with odynophagia
- Overheating / inadequate intake
Red flags
- Sunken fontanelle
- Absent tears when crying
- Capillary refill >3 seconds
- Altered mental status or lethargy
- Tachycardia with delayed perfusion
- No urine output >8 hours
- Projectile vomiting in infant 2-8 weeks (pyloric stenosis)
Workup
- history: Duration and frequency of vomiting and diarrhea; Last wet diaper / urination; Oral intake attempts; Sick contacts; Projectile vomiting pattern (pyloric stenosis); Polyuria and polydipsia (DKA); exam: Weight comparison to recent well-child visit; Mucous membranes: moist vs dry vs parched; Fontanelle: flat vs sunken; Skin turgor: tenting?; Capillary refill; Mental status: alert vs irritable vs lethargic; labs: BMP: electrolytes, glucose, BUN/Cr; Urinalysis: specific gravity, ketones; Blood gas if moderate-severe dehydration; Serum glucose if lethargic or altered; imaging: Abdominal ultrasound if pyloric stenosis suspected (olive mass, projectile vomiting); Ultrasound or air enema if intussusception suspected; bedside: Point-of-care glucose; Weight
Management
- immediate: 20mL/kg NS bolus if signs of shock (repeat up to 60mL/kg); Check glucose and correct if low; Ondansetron 0.15mg/kg ODT or IV (max 4mg) for vomiting; general: Classify dehydration: mild (3-5%), moderate (6-9%), severe (≥10%); Oral rehydration therapy (ORT) is first-line for mild-moderate: 50-100mL/kg over 4 hours; specific: diagnosis: Mild-moderate dehydration; steps: ORT with Pedialyte: 5mL q5min, gradually increase; Ondansetron to facilitate oral rehydration; If tolerating ORT after 4 hours, discharge with instructions; Return if unable to keep fluids down or worsening; diagnosis: Severe dehydration; steps: 20mL/kg NS bolus, reassess, repeat as needed; Maintenance IV fluids: D5 0.45% NS with 20mEq/L KCl (once voiding); Monitor electrolytes q4-6h; Address underlying cause; diagnosis: Pyloric stenosis; steps: NPO, NG tube decompression; Correct metabolic alkalosis: NS bolus, then D5 0.45% NS with KCl; Surgical consult for pyloromyotomy; Monitor chloride and potassium closely
Disposition
- admit: Severe dehydration (≥10%); Failed oral rehydration trial; Intractable vomiting despite ondansetron; Electrolyte abnormalities requiring correction; Suspected surgical condition (pyloric stenosis, intussusception); discharge: Mild dehydration tolerating ORT; Moderate dehydration after successful ED rehydration; Reliable caregivers with clear return precautions; consults: Pediatric surgery for pyloric stenosis or intussusception; Endocrinology if DKA
Clinical pearls
- Ondansetron for vomiting significantly increases ORT success and reduces IV fluid need and admission rates
- Best dehydration assessment: combination of capillary refill, skin turgor, and respiratory pattern — no single sign is reliable alone
- Pyloric stenosis classic electrolyte pattern: hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduria
- Weight-based dehydration calculation: (pre-illness weight - current weight) / pre-illness weight × 100 = % dehydration
Source and review
- AAP Gastroenteritis Guidelines 2004 (reaffirmed), WHO ORT Guidelines, ESPGHAN/NASPGHAN Guidelines. Last reviewed: 2024-11-01