Nitrogen balance

1. It is the difference between nitrogen intake and nitrogen loss in an individual.

2. Intake of nitrogen occur in the form of protein/amino acid, since they contain amino acid and the nitrogen content of protein is about 16%; that means 100 gm protein contains 16 gm nitrogen. An adult individual usually consumes about 75-100 gm protein. So their nitrogen intake is about 12-16gm/day.

3. Protein/amino acid are catabolized in human body into different nitrogenous substances which are excreted out from the body, so protein/amino acid excreted from the body occur in the form of nitrogen.

4. Types of nitrogen balance:

·        Nitrogen equilibrium: here nitrogen intake = nitrogen output. Seen in normal adults.

·        Positive nitrogen balance: Here intake of nitrogen is greater than excretion. Positive nitrogen balance observed in situations in which tissue growth occurs for example in children, pregnancy or during recovery from an emaciating disease.

Negative nitrogen balance: Here nitrogen intake is less excretion is more. Negative nitrogen is associated with inadequate dietary protein, lack of an essential amino acid or during physiologic stresses such as trauma, burns, illness or surgery.