Urea nitrogen is the end product of breakdown of proteins in the body.
In individuals with normal kidney and liver functions, urea is excreted via urine.
Calculating nitrogen balance is a useful tool in assessing adequacy of protein provision in clinical setting in: UUN is determined from 24-hour urine collection.
Along with UUN, values for BUN, protein content of diet, enteral or parenteral nutrition, and notable outputs other than urine (gastric residual, fistula output, drainages) are needed to calculate nitrogen balance.
Nitrogen Balance = Protein intake/6.25- (UN + 4*) * For average loss via sweat and feces.