Nitrogen balance is the measure of nitrogen output subtracted from nitrogen input.[1]
Blood urea nitrogen can be used in estimating nitrogen balance, as can the urea concentration in urine.
A positive value is often found during periods of growth, tissue repair or pregnancy. This means that the intake of nitrogen into the body is greater than the loss of nitrogen from the body, so there is an increase in the total body pool of protein.
A negative value can be associated with burns, fevers, wasting diseases and other serious injuries and during periods of fasting. This means that the amount of nitrogen excreted from the body is greater than the amount of nitrogen ingested.[2]
It can be used in the evaluation of malnutrition.[3]