Note: Positive nitrogen balance means you have a build-up of ammonia, ie, your urea cycle is backed-up. One of the products of the urea cycle is Arginine—it's the only place in the body where Arginine is made in fact. So if your urea cycle is messed up, you're going to need to get your Arginine from somewhere else, like your diet.

Note: Arginine is the last step of the Urea cycle before Urea is made from the excess NH4. So, if there is a lot of protein being metabolized and NH4 being made, then you want it converted to urea as quickly as possible. In practical use, if a kid has a urea cycle disorder (e.g. citrullinemia), they will have an insanely high level of NH4, because the cycle is halted downstream, and the body is not making argininosuccinate, which is then converted to arginine. One part of the treatment is to flood them with IV arginine so that the urea cycle can skip ahead to the step where it converts into Urea.

Mnemonic: PVT. TIM HALL

Note: Arginine is only essential during (+) Nitrogen Balance.