Infants, especially newborns and those under 1 year of age, are more vulnerable to fluid and electrolyte imbalances compared to older children and adults. This is because of their unique physiological characteristics, immature organs, and rapid growth needs. Below are the main reasons:
1. Higher Percentage of Body Water
- Infants have more body water content than adults—about 70% to 80% of their body weight is water.
- A larger proportion of this water is in the extracellular compartment, which is more rapidly lost during illness.
2. Immature Kidneys
- Infants’ kidneys are not fully mature until about 1 year of age.
- They are less efficient in:
- Concentrating urine
- Conserving sodium
- Excreting excess water
- This immaturity makes it difficult to regulate fluid and electrolyte levels effectively.
3. Higher Metabolic Rate
- Infants have a high basal metabolic rate, which increases:
- Heat production
- Water loss through respiration and skin
- Nutrient and oxygen demand
- This leads to increased fluid requirement and risk of dehydration.
4. Greater Surface Area-to-Body Weight Ratio
- Infants have a larger surface area relative to their body weight.
- This results in more fluid loss through the skin, especially in hot climates like India or during fever.
5. Poor Communication Ability
- Infants cannot express thirst or discomfort effectively.
- They rely completely on caregivers for fluid intake and care, making them vulnerable to unrecognized dehydration.
6. Rapid Fluid Turnover
- Due to high water content and metabolic demands, infants have rapid turnover of fluids.
- Even mild illness (e.g., fever, diarrhea, vomiting) can lead to significant loss of fluids and electrolytes quickly.
7. Dependence on Liquid Diet
- Infants are typically fed only breast milk or formula.
- If feeding is interrupted due to illness or poor intake, they do not receive adequate fluids, increasing dehydration risk.
8. Immature Immune System
- Infants are more prone to infections, especially gastrointestinal infections like diarrhea.
- These illnesses cause rapid fluid and electrolyte loss, especially sodium, potassium, and chloride.
9. Increased Insensible Water Loss
- Water loss that occurs through:
- Lungs (respiration)
- Skin (sweating)
- This is higher in infants due to increased respiratory rate and thin skin.
10. Inadequate Reserve of Electrolytes
- Infants have low reserve of electrolytes, particularly:
- Sodium (Na⁺)
- Potassium (K⁺)
- Bicarbonates (HCO₃⁻)
- Therefore, even a small loss can cause major imbalances and metabolic disturbances.
Conclusion
Infants are at high risk for fluid and electrolyte imbalances due to multiple factors such as immature kidneys, high metabolic rate, poor communication, and physiological dependency. Caregivers and health professionals must be vigilant in monitoring signs of dehydration, ensuring proper feeding, and promptly treating any illness to avoid complications.