Organic Acids (Complete), Urine (Sendout)

Clinical Utility: Urine organic acids can be used for diagnosis and monitoring in patients with disorders of amino acid, organic acid, and fatty acid metabolism. This test is often used in conjunction with plasma acylcarnitines for follow up of presumptive positives in the newborn screening program. The following conditions typically show abnormalities in the urine organic acid profile: Alcaptonuria (homogentisic acid), Biotinidase deficiency, Canavan disease (N-acetylaspartic acid), Fatty Acid Oxidation Defects (MCAD, VLCAD, LCHAD), Fructose-1,6-diphosphatase deficiency (glycerol), Fumarase deficiency, Glutaric aciduria type 1 & 2, Glycerol kinase deficiency (glycerol), Hawkinsinuria (4-hydroxycyclohexylacetic acid), HMG CoA lyase deficiency, Holocarboxylase synthase deficiency, Hyperoxaluria type 1 & 2, Isovaleric aciduria, Ketosis, Ketothiolase deficiency, Malonyl-CoA dehydrogenase deficiency, Maple Syrup Urine Disease, Methylmalonic aciduria, 3-methylcrotonyl CoA carboxylase deficiency, Mevalonic aciduria (mevalonolactone), Multiple acyl-CoA dehydrogenase deficiency (glutaric aciduria type 2), Multiple carboxylase deficiency, Ornithine transcarbamylase deficiency (orotic acid), Phenylketonuria, Propionic aciduria, Succinic semialdehyde dehydrogenase deficiency (4-hydroxybutyric acid), Tyrosinemia type 1 (succinylacetone), and Tyrosinemia type 2.

Test Description: Organic acids are extracted from urine at acid pH with ethyl acetate and ether, and derivatized with hydroxylamine and BSTFA. Separation is accomplished by gas chromatography and identification by mass spectrometry using a library of 200 compounds. Semi-quantitative results are reported for 13 organic acids. The following organic acids are always reported: 2-Ketoglutaric, 3-Methylglutaconic, 3-Methylglutaric, 3-OH-Butyric Acid, Acetoacetic, Adipic, Ethylmalonic, Fumaric, Glutaric, Lactic, Pyruvic, Sebacic, and Suberic acids. Other clinically relevant organic acids will be reported, if present.

Collection Timing: Samples are best collected while patient is ill. Testing asymptomatic patients may yield false negative results. Succinylacetone is included in this test, however, please note if tyrosinemia type 1 is suspected. Quantitative succinylacetone is suggested for follow-up monitoring of confirmed patients.

Ordering Requirements: Include relevant clinical information (drug therapy, family history, etc.) in the Epic order comment to ensure proper interpretation.