N-Propionylglycine is a glycine-conjugated form of propionic acid.¹It is produced by glycine-N-acylase from propionyl-CoA, a catabolic intermediate that accumulates when the activity of propionyl-CoA carboxylase, the enzyme that converts propionyl-CoA to methylmalonyl-CoA, is deficient, in the mitochondria.^1,2Urinary levels of N-propionylglycine are increased in patients with propionic acidemia, an inborn error of metabolism characterized by vomiting, lethargy, protein intolerance, and failure to thrive.¹

1.Riemersma, M., Hazebroek, M.R., Helderman-van den Enden, A.T.J.M., et al.Propionic acidemia as a cause of adult-onset dilated cardiomyopathyEur. J. Hum. Genet.25(11)1195-1201(2017) 2.Fong, B.M.-W., Tam, S., and Leung, S.-Y.Quantification of acylglycines in human urine by HPLC electrospray ionization-tandem mass spectrometry and the establishment of pediatric reference interval in local ChineseTalanta88193-200(2012)