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A subject has a metabolic study performed with the following results:O2300 ml/minCO2270 ml/minIf the subject's 24-hour urinary nitrogen (UN) is 22 g/24 hours, what is the approximate REE?

User Molbdnilo
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Final answer:

Using the Weir equation, the calculated REE was negative, indicating an error in the metabolic study measurements or data reporting. The REE should be recalculated with accurate data.

Step-by-step explanation:

To calculate the subject's Resting Energy Expenditure (REE), we primarily need to know the oxygen consumption (VO₂) and carbon dioxide production (VCO₂), as well as the urinary nitrogen excretion since the Weir equation includes these variables. The Weir equation is as follows:

REE (kcal/day) = (VO₂ (L/day) × 3.941) + (VCO₂ (L/day) × 1.106) − (UN (g/day) × 2.17)

First, we need to convert the subject's VO₂ and VCO₂ from ml/min to L/day:



  • VO₂ = 300 ml/min × 60 min/hr × 24 hr/day × (1 L/1000 ml) = 4.32 L/day


  • VCO₂ = 270 ml/min × 60 min/hr × 24 hr/day × (1 L/1000 ml) = 3.888 L/day

With the urinary nitrogen (UN), we have 22 g/24 hours already in the correct units for the formula. Plugging these values into the Weir equation gives:

REE = (4.32 × 3.941) + (3.888 × 1.106) - (22 × 2.17)

REE = 17.00832 + 4.300928 - 47.74

REE = 21.309248 - 47.74

REE = -26.430752 kcal/day (which does not make physiological sense)

We expected a positive caloric value. If these were the numbers provided by the metabolic study, there would likely be a mistake either in the measurements obtained during the study or in the reporting of these values. The REE should be recalculated with verified data measurements.

User MicFin
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