Nitrogen Balance

If the total daily nitrogen losses in urine, skin, and feces are equal to the total daily nitrogen intake, the subject is said to be in nitrogen balance, as healthy, adequately fed adult should be.

Excretion in the urine disposes of about 90% of the nitrogen lost from the body with urinary urea accounting for 70% to 85% of the total urinary nitrogen, depending upon nitrogen intake. Losses also occur through the skin, mainly as sweat, and via the feces.

Positive Nitrogen Balance

If nitrogen losses are less then intake the subject is said to be in positive nitrogen balance as healthy, growing children and convalescing adults should be.

Negative Nitrogen Balance

If nitrogen losses are greater then intake the subject is said to be in negative nitrogen balance, as in diseases involving tissue wasting or starvation. Prolonged periods of negative nitrogen balance are dangerous and are fatal if the loss of body protein reaches about one-third of the total body protein.

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