A high level of ornithine typically indicates a deficiency in the enzyme that breaks down ornithine, called ornithine transcarbamylase. This can lead to a condition called ornithine transcarbamylase deficiency, which results in the build-up of ammonia in the blood. This condition can be life-threatening and requires immediate medical attention.

OTC usually stands for Over The Counter. It also stands for Ornithine transcarbamylase.
"OTC" stands for "over-the-counter," which in the US means that you can purchase that medication without a prescription.

C5H12N2O2

The metabolic product of arginine is ornithine and urea. The amino acid arginine is degraded by the enzyme arginase into ornithine and urea. The ornithine can be converted to glutamate that is oxidized to alpha ketoglutarate before it enters the kreb cycle.

Ornithine