Ornithine is an important intermediate in the production of urea, the primary route of excretion of excess nitrogen in the urine. Ornithine can also be back-converted to arginine if concentrations of arginine are low. In this sense, ornithine is a precursor to nitric oxide as well. Like arginine, ornithine has been shown to stimulate the release of growth hormone. A salt of this amino acid called ornithine alpha-ketoglutarate has been shown to be more effective than either of its components as an anabolic.