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Institute of
Dietitians
Guidelines Clinical Tools Certification About
Clinical Tool

Nitrogen Balance Calculator

Assess protein adequacy using UUN.

JavaScript Required

This interactive calculator requires JavaScript to function. To manually calculate, use the formula below:

Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Patient Parameters

Results

Basal Metabolic Rate
kcal/day
Estimated Energy Requirement
kcal/day

* Calculation uses the Mifflin-St Jeor equation, widely validated for healthy and obese populations. Not validated for critical illness (indirect calorimetry or Penn State equation preferred).

Clinical Context & Assumptions

The Mifflin-St. Jeor equation is the most reliable equation for predicting resting energy expenditure (REE) in healthy nonobese and obese individuals (ASPEN guidelines). However, its utility in critical illness is limited.

Formulas Used

  • Men: REE = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
  • Women: REE = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Next steps: Review our other calculation tools, read the Critical Care Guidelines, or navigate back to the home page.