Ureidopropionic acid (3-Ureidopropionic acid) is an intermediate in the metabolism of uracil. More specifically it is a breakdown product of dihydrouracil and is produced by the enzyme dihydropyrimidase. It is further decomposed to beta-alanine via the enzyme beta-ureidopropionase. Ureidopropionic acid is essentially a urea derivative of beta-alanine. High levels of Ureidopropionic acid are found in individuals with beta-ureidopropionase (UP) deficiency. Enzyme deficiencies in pyrimidine metabolism are associated with a risk for severe toxicity against the antineoplastic agent 5-fluorouracil.