Description General description Homogentisic acid (HGA) is an intermediate formed during the catabolism of phenylalanine and tyrosine. Alkaptonuria, a metabolic disorder, is characterized by high levels of HGA in serum and urine due to the deficiency of the enzyme homogentisic acid oxidase, which is involved in the degradation of HGA. Packaging 100, 500 mg in poly bottle Other Notes Tandem Mass Spectrometry data independently generated by Scripps Center for Metabolomics is available to view or download in PDF. H0751.pdf Tested metabolites are featured on Scripps Center for Metabolomics METLIN Metabolite Database. To learn more, visit sigma.com/metlin.