Is arginine a conditionally essential amino acid?
In young rats, cats, and dogs, arginine has been shown to be an essential nutrient and elimination of this substance from the diet can limit optimal growth (5,6). This is not the case for humans under normal circumstances. However, there may be some situations where arginine can be thought of as a conditionally essential amino acid. For example, Heird and associates (7) described 3 premature infants who received an imbalanced intravenous feeding solution composed of crystalline amino acids, free of arginine, at a dose of 2.5 g · kg 1 · d 1. Hyperammonemia occurred but resolved with the administration of parenteral arginine. In another study, Batshaw and associates reported that 50% of premature infants weighing <2,500 g had elevated ammonia levels within the first 2 months of life when compared to infants weighing >2,500 g (8). When arginine and ornithine levels were compared in 2 groups of matched infants, with one group having normal ammonia levels and the other group having elevated
