Calculating Energy and Protein Requirements in Pediatric Patients
Use the Schofield equation based on weight to calculate resting energy expenditure (REE), then adjust for physical activity, disease state, and catch-up growth needs to determine total energy requirements. 1
Energy Requirement Calculation Algorithm
Step 1: Calculate REE Using Schofield Equations
The Schofield equation is the preferred method as it was least likely to underestimate REE compared to measured values 1. Apply the age- and sex-specific formulas:
Schofield Equations for REE (kcal/day):
- Ages 0-3 years:
- Boys: 59.5 × (weight in kg) + 30
- Girls: 58.3 × (weight in kg) + 31
- Ages 3-10 years:
- Boys: 22.7 × (weight in kg) + 504
- Girls: 20.3 × (weight in kg) + 486
- Ages 10-18 years:
- Boys: 17.7 × (weight in kg) + 658
- Girls: 13.4 × (weight in kg) + 692
Step 2: Adjust for Clinical Context
For stable patients receiving parenteral nutrition, calculate total energy needs by adding constants for:
- Physical activity level (PAL)
- Catch-up growth requirements
- Disease-specific factors that increase or decrease REE
Alternatively, you can double the REE for a simplified approach 1.
Quick reference energy targets (kcal/kg/day) by age and disease phase:
| Age Group | Acute Phase | Stable Phase | Recovery Phase |
|---|---|---|---|
| Preterm | 90-120 | 60-65 | 45-55* |
| 0-1 year | 75-85 | 60-65 | 45-50 |
| 1-7 years | 65-75 | 55-60 | 40-45 |
| 7-12 years | 55-65 | 40-55 | 30-40 |
| 12-18 years | 30-55 | 25-40 | 20-30 |
*For premature neonates on first day of life 1
Step 3: Consider Special Circumstances
When indirect calorimetry is indicated:
- Children with suspected metabolic alterations
- Severe malnutrition or moderate-to-severe failure to thrive
- When precise caloric needs are critical for optimal care
Important caveat: Standard predictive equations can be unreliable and may only accurately predict REE in approximately 40% of patients 2. The Schofield equation using both weight and height performs better than weight-alone equations, but still has limitations 2, 3.
Protein Requirement Calculation
By Age Group:
Infants and children (1 month to 3 years):
- Minimum: 1.0 g/kg/day to avoid negative nitrogen balance
- Maximum: 2.5 g/kg/day for stable patients 4
Children (3-12 years):
- Range: 1.0-2.0 g/kg/day for stable patients
- Critically ill may require up to 2.8 g/kg/day based on nitrogen balance studies 4
Adolescents:
- Range: 1.0-2.0 g/kg/day for stable patients 4
Premature infants:
- Specific requirements vary based on gestational age and clinical status
- Target weight gain of 17-20 g/kg/day in very low birth weight infants 1
Critical Clinical Considerations
Physical Activity Levels (PAL)
Most hospitalized children have low PALs:
- 1.0 for sleeping
- 1.2 for lying awake or sitting quietly
- 1.4-1.5 for standing or sitting activities
- 1.7 for moderate activity (healthy children) 1
Growth Energy Costs
- Infants 0-3 months: ~175 kcal/day
- Infants 4-6 months: ~60 kcal/day
- Infants 6-12 months: ~20 kcal/day
- Healthy children/adolescents: 20-30 kcal/day (higher at peak growth velocity) 1
Critically Ill Children
Important evidence: A large multicenter RCT (PEPaNIC study) showed that withholding parenteral nutrition for up to 1 week in critically ill children while providing micronutrients was clinically superior to early PN, resulting in fewer infections, reduced ventilator time, and earlier discharge 4. This applies to term infants, children, and adolescents in the PICU setting.
Common Pitfalls to Avoid
Don't rely solely on predictive equations in metabolically complex patients—use indirect calorimetry when available 1
Account for route of administration: Parenteral nutrition requirements differ from enteral due to differences in diet-induced thermogenesis and absorption losses 1
Avoid overfeeding in acute phase: Energy needs may be lower than predicted, particularly in the first days of critical illness 1
Consider malabsorption and losses: Factor in energy losses from wounds, diarrhea, and malabsorption when calculating total needs 1
Monitor and adjust: Predictive equations have significant variability—continuously assess growth parameters, weight changes, and clinical response to modify prescriptions 1, 2