How are oral rehydration solutions used in the treatment of dehydration?

Updated: Dec 07, 2018
  • Author: Lennox H Huang, MD, FAAP; Chief Editor: Timothy E Corden, MD  more...
  • Print
Answer

During gastroenteritis, the intestinal mucosa retains absorptive capacity. Sodium and glucose in the correct proportions can be passively cotransported with fluid from the gut lumen into the circulation. Rapid oral rehydration with the appropriate solution has been shown to be as effective as intravenous fluid therapy in restoring intravascular volume and correcting acidosis.

Table 3. Composition of Appropriate Oral Rehydration Solutions (Open Table in a new window)

Solution

Carbohydrate (g/dL)

Sodium (mEq/L)

Potassium (mEq/L)

Base (mEq/L)

Osmolality

Pedialyte

2.5

45

20

30

250

Infalyte

3

50

25

30

200

Rehydralyte

2.5

75

20

30

310

The World Health Organization (WHO) and United Nations International Children's Emergency Fund (UNICEF) have a standard and reduced osmolarity formulation of their oral rehydration solution.

Table 4. WHO-UNICEF Oral Rehydration Solutions (Open Table in a new window)

Solution

Sodium

(mEq/L)

Chloride

(mEq/L)

Glucose, Anhydrous

(mEq/L)

Potassium

(mEq/L)

Citrate

(mEq/L)

Osmolality

Standard

90

80 111 20 10 311

Reduced osmolarity 

75

65 75 20 10 245

UNICEF = United Nations International Children's Emergency Fund, WHO = World Health Organization. [16, 17]

All of the commercially available rehydration fluids are acceptable for oral rehydration therapy (ORT). They contain 2-3 g/dL of glucose, 45-90 mEq/L of sodium, 30 mEq/L of base, and 20-25 mEq/L of potassium. Osmolality is 200-310 mOsm/L.

In children with severe acute malnutrition and diarrhea, low osmolarity oral rehydration solution (ORS) (osmolarity: 245, sodium: 75 mEq/L) with added potassium (20 mmol/L) appears to be equally effective for successful rehydration as modified World Health Organization–recommended rehydration solution (ReSoMal) (osmolarity: 300, sodium: 45 mEq/L) but achieves rehydration more quickly. [18]  Both solutions also correct for hypokalemia, but hyponatremia may affect fewer children with the low-osmolarity ORS formulation. These findings indicate that the low osmolarity ORS may be an option in regions where ReSoMal is not available (eg, India). [18]

Table 5. Composition of Inappropriate Oral Rehydration Solutions (Open Table in a new window)

Solution

Carbohydrate (g/dL)

Sodium (mEq/L)

Potassium (mEq/L)

Base (mEq/L)

Osmolality

Apple juice

12

0.4

26

0

700

Ginger ale

9

3.5

0.1

3.6

565

Milk

4.9

22

36

30

260

Chicken broth

0

2

3

3

330

Traditional clear fluids are not appropriate for ORT. Many contain excessive concentrations of CHO and low concentrations of sodium. The inappropriate glucose-to-sodium ratio impairs water absorption, and the large osmotic load creates an osmotic diarrhea, further worsening the degree of dehydration.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!