Orotic Acid Unit Converter

Orotic acid is a naturally occurring compound that serves as an intermediate in the body's production of pyrimidines, the building blocks used to make DNA and RNA. It was once called vitamin B13 after its discovery in cow's milk, but it is not a true vitamin.

A blood test for orotic acid measures how well the pyrimidine synthesis pathway and the urea cycle are functioning. Under normal conditions, orotic acid is rapidly converted into uridine monophosphate (UMP) and does not accumulate. When it builds up, it signals a block in either pyrimidine metabolism or nitrogen disposal.

Orotic acid is most commonly tested when a urea cycle disorder is suspected, because it helps distinguish which enzyme in the cycle is deficient.

Orotic acid is produced in most nucleated cells as part of the de novo pyrimidine synthesis pathway. The liver is the most clinically relevant site because it houses the urea cycle, and urea cycle defects cause the overflow of carbamoyl phosphate that drives orotic acid accumulation.