Nitrogen Balance
Start with the big picture
Nitrogen balance is calculated as nitrogen intake minus nitrogen loss. A zero balance is associated with adequate protein nutrition in healthy, non-growing adults; positive balance occurs when intake exceeds loss, as in growth, pregnancy, and recovery. Negative balance can accompany malnutrition, severe illness, injury, or other catabolic states. Most nitrogen is lost in urine, largely as urea, while feces, skin, and sweat contribute additional losses. Interpretation also depends on protein quality, essential amino acid sufficiency, adequate energy intake, and hormonal influences. The deeper lesson explores how nitrogen balance is assessed, including limitations that matter in conditions such as renal failure or urea cycle disorders.
What you'll learn
- Define nitrogen balance and state how it is calculated.
- Distinguish zero, positive, and negative nitrogen balance.
- Identify major routes and forms of nitrogen loss.
- Explain how protein quality, energy intake, and hormones affect balance.
- Describe factors that complicate nitrogen balance assessment.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
