Treatment of Moderate Dehydration
For moderate dehydration (6%-9% fluid deficit), administer oral rehydration solution (ORS) at 100 mL/kg over 2-4 hours as first-line therapy. 1
Clinical Assessment
Moderate dehydration presents with specific physical findings that guide treatment intensity:
- Loss of skin turgor with tenting when pinched 1
- Dry mucous membranes 1
- Decreased capillary refill time (correlates well with fluid deficit) 1
- Rapid, deep breathing (indicates acidosis and more reliably predicts dehydration than sunken fontanelle or absent tears) 1
Rehydration Protocol
Oral Rehydration Solution (First-Line)
Administer reduced osmolarity ORS containing 50-90 mEq/L sodium at 100 mL/kg over 2-4 hours. 1 This represents strong evidence with moderate quality for all age groups. 1
Practical administration technique:
- Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper 1
- Gradually increase the amount as tolerated 1
- Reassess hydration status after 2-4 hours 1
If rehydration is successful, transition to maintenance therapy. 1
If dehydration persists, reestimate the fluid deficit and restart rehydration therapy. 1
Alternative Routes When Oral Intake Fails
Nasogastric administration of ORS may be considered for patients who cannot tolerate oral intake or children with normal mental status who are too weak or refuse to drink adequately. 1 This carries weak evidence with low quality but provides a practical bridge before IV therapy. 1
When to Escalate to Intravenous Therapy
Switch to isotonic IV fluids (lactated Ringer's or normal saline) if: 1
- Patient cannot tolerate oral rehydration 1
- Altered mental status develops 1
- Signs of shock appear 1
- Ileus is present 1
- Ketonemia prevents tolerance of oral fluids 1, 2
This recommendation carries strong evidence with high quality. 1
Ongoing Loss Replacement
During rehydration, continuously replace ongoing losses: 1
- 10 mL/kg for each watery or loose stool 1
- 2 mL/kg for each episode of vomiting 1
- Use ORS containing 40-90 mEq/L sodium 1
Maintenance Phase
Once rehydrated, administer maintenance fluids and replace ongoing losses with ORS until diarrhea and vomiting resolve. 1 This carries strong evidence despite low quality. 1
Resume age-appropriate diet immediately after or during rehydration completion. 1 Continuing nutrition during illness improves outcomes. 1
Special Considerations
Presence of Ketones
If ketones are present (indicating ketosis):
- Initial IV hydration may be needed to enable tolerance of oral rehydration 1, 2
- Include carbohydrate intake (150-200g per day) to resolve ketosis 2
- Monitor for resolution through urine or blood testing 2
Infants and Children
Breast-fed infants should continue nursing on demand throughout treatment. 1 This carries strong evidence with low quality. 1
For bottle-fed infants, resume full-strength formula immediately upon rehydration. 1
Common Pitfalls to Avoid
Do not use sports drinks, juice, soft drinks, or chicken broth as primary rehydration fluids in moderate dehydration—these lack appropriate sodium and glucose concentrations. 3 Reserve these only for mild or no dehydration. 3
Avoid antimotility drugs (loperamide) in children <18 years with acute diarrhea, as this carries strong evidence with moderate quality. 1 In adults, avoid loperamide if inflammatory diarrhea or fever is present due to toxic megacolon risk. 1
Do not delay treatment waiting for laboratory results—clinical assessment is sufficient to initiate therapy. 1 Serum electrolytes are only needed when clinical signs suggest specific abnormalities. 1