Phenylpyruvic

- Moderate elevations may result from intake of phenylalanine, from genetic carrier status for PKU, or from a deficiency in production of biopterin, a cofactor required for phenylalanine metabolism. 

- Very high values are associated with the genetic disease, PKU.

PKU is due to lack of the enzyme phenylalanine hydroxylase (PAH), so that phenylalanine is converted not to tyrosine but to phenylpyruvic acid. In particular, excessive phenylalanine can be metabolized into phenylketones through, a transaminase pathway route involving glutamate. Metabolites of this transamination reaction include phenylacetate, phenylpyruvate and phenethylamine. In persons with PKU, dietary phenylalanine either accumulates in the body or some of it is converted to phenylpyruvic acid. Individuals with PKU tend to excrete large quantities of phenylpyruvate, phenylacetate and phenyllactate, along with phenylalanine, in their urine.

- Biopterin deficient people may benefit from supplementation with the folate derivative folinic acid.

Phenylpyruvic acid is a keto-acid that is an intermediate or catabolic byproduct of phenylalanine metabolism. It has a slight honey-like odor.