$690 Organic Acids, Full Panel, Quantitative, Urine (Quest Diagnostics)

Organic Acids, Full Panel, Quantitative, Urine

http://www.questdiagnostics.com/testcenter/testguide.action?dc=TS_OrgAcFull

Clinical Use

Diagnose organic acidurias

Clinical Background

Organic acidurias are inherited disorders resulting from a deficient enzyme or transport protein. Although most are autosomal recessive disorders, several are X-linked. The more than 60 described organic acidurias affect many metabolic pathways including amino acid metabolism, lipid metabolism, purine and pyrimidine metabolism, the urea cycle, the Krebs cycle, and fatty acid oxidation. These disorders are characterized by a wide variety of symptoms such as lethargy, coma, hypotonia, seizures, ataxia, vomiting, failure to thrive, developmental delay, liver disease, neutropenia, thrombocytopenia, osteomalacia, and osteoporosis. Severity of presentation is highly variable as is age of onset, and patients may not present with the most characteristic features. Laboratory results commonly indicate metabolic acidosis, increased anion gap, hyperammonemia, hypoglycemia, lactic acidemia, ketosis, or abnormal lipid patterns. Treatment may be based on dietary restrictions and/or supplementation with cofactors (eg, riboflavin or cobalamin) or conjugating agents (eg, carnitine or sodium benzoate); however, there is no effective therapy for some of the disorders.

Individuals Suitable for Testing

Infants Children Adults

Method

Gas chromatography/mass spectrometry Quantitates 78 organic acids Reported results: mmol/mol creatinine and a patient specific interpretation Turn-around-time: 4-6 days

Interpretive Information

Elevation of one or more organic acids is diagnostic for an organic aciduria; however, elevations should be interpreted in context with clinical findings and/or additional test results. Since many organic acidurias are episodic, the diagnostic efficacy is maximized when the patient is expressing symptoms at the time of specimen collection. The Table lists selected organic acidurias along with the organic acids that may be elevated in each disorder. Only those organic acids included in this test are listed. Table. Selected Organic Acidurias and Associated Organic Acid Elevations Organic Aciduria Elevated Organic Acid Methylmalonic acidemia Methylmalonic acid, methylcitric acid, 3-hydroxypropionic acid, propionylglycine, 3-hydroxyvaleric acid Fatty oxidation defects (medium chain  acyl-CoA dehydrogenase deficiency [MCAD]) Adipic acid, suberic acid, sebacic acid, octanoic acid, suberylglycine, hexanoylglycine, octenedioic acid, phenylpropionylglycine, 5-hydroxyhexanoic acid Propionic acidemia Propionylglycine, methylcitric acid, 3-hydroxypropionic acid, 3-hydroxyvaleric acid Glutaric aciduria, type 1 Glutaric acid, glutaconic acid, 3-hydroxyglutaric acid Multiple acyl-CoA dehydrogenase deficiency (glutaric aciduria, type II) Glutaric acid, adipic acid, suberic acid, 2-hydroxyglutaric acid, ethylmalonic acid, isovalerylglycine Isovaleric acidemia Isovalerylglycine, 3-hydroxyisovaleric acid Multiple carboxylase deficiency 3-Methylcrotonylglycine, methylcitric acid, lactic acid, 3-hydroxyisovaleric acid, tiglylglycine, 3-hydroxypropionic acid Urea cycle defects Orotic acid Maple syrup urine disease (MSUD) 2-Oxoisocaproic acid, 2-hydroxyisocaproic acid, 2-hydroxyisovaleric acid, 2-oxoisovaleric acid, 2-hydroxy-3-methylvaleric acid, 2-oxo-3-methylvaleric acid Lactic acidosis Lactic acid, pyruvic acid, 2-hydroxybutyric acid, 4-hydroxyphenyllactic acid Tyrosinemia 4-Hydroxyphenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenylpyruvic acid, N-acetyltyrosine, succinylacetone (type I only) Canavan disease N-acetylaspartic acid Ketosis Acetoacetic acid, 3-hydroxybutyric acid, adipic acid, suberic acid, 3-hydroxyisobutyric acid, 3-hydroxyisovaleric acid, 3-hydroxy-2-methylbutyric acid Phenylketonuria (PKU) Phenyllactic acid, phenylpyruvic acid, 2-hydroxyphenylacetic acid 2-Oxoadipic aciduria 2-Oxoadipic acid, 2-hydroxyadipic acid 3-Hydroxy-3-methylglutaric aciduria 3-Hydroxy-3-methylglutaric acid, 3-hydroxyisovaleric acid, 3-methylcrotonylglycine, 3-methylglutaconic acid, 3-methylglutaric acid 3-Methylcrotonyl-CoA carboxylase deficiency 3-Hydroxyisovaleric acid, 3-methylcrotonylglycine 3-Methylglutaconic aciduria 3-Methylglutaconic acid, 3-hydroxyisovaleric acid, 3-methylglutaric acid 3-Oxothiolase deficiency 3-Hydroxy-2-methylbutyric acid, tiglylglycine, 2-methylacetoacetic acid, acetoacetic acid, 3-hydroxybutyric acid 5-Oxoprolinuria 5-Oxoproline Dihydrolipoyl dehydrogenase deficiency (lipoamide dehydrogenase, E3) Lactic acid, 2-hydroxyisocaproic acid, 2-hydroxyisovaleric acid, 2-hydroxy-3-methylvaleric acid, 2-oxoglutaric acid, 2-oxoisocaproic acid, 2-oxoisovaleric acid, 2-oxo-3-methylvaleric acid