Diagnosis of inborn errors of metabolism
This test provides a qualitative report of abnormal levels of organic acids identified via gas chromatography mass spectrometry.
Diagnostic specificity of inborn errors of metabolism via urine organic acids analysis is variable due to factors such as specimen collection when the patient is asymptomatic versus acutely ill, taking dietary supplements, or anabolic versus catabolic status of the patient.
Gas Chromatography Mass Spectrometry (GC-MS)
Lactic
Pyruvic
3-OH Propionic
3-OH Butyric
3-OH Isobutyric
Acetoacetic
2-Methyl 3-OH Butyric
3-OH Isovaleric
2-OH Isovaleric
Malonic
MMA
GHB
4-OH Butyric
Ethylene Glycol
2-Ketoisovaleric
2-Methyl Acetoacetic
Ethylmalonic
Succinic
Fumaric
Uracil
Thymine
Trans-3-hydroxyhexenoic
Trans-5-hydroxyhexenoic
Erythro-2,3-dihydroxy 2-methylbutyric
Mevalonic
Isobutyrylglycine
Glutaric
3-Methylglutaconic
Propionylglycine
2-Methylbutyrylglycine
Adipic
2-Ketoglutaric
Isovalerylglycine
3-OH 3-Methylglutaric
4-OH 6-methyl 2-pyrone
4HMP
Malic
Pyroglutamic
5-Oxoproline
3-Methylcrotonylglycine
Tiglylglycine
2-OH Glutaric
3-OH Glutaric
Succinylacetone
Hexanoylglycine
N-Acetylaspartic
2-OH Adipic
Octenedioic
Suberic
2-Ketoadipic
2-Oxoadipic
Orotic
Hippuric
Pyrrole-2-Carboxyglycine
Homogentisic
Methylcitric
Sebacic
Vanillylmandelic
VMA
Homovanillic
HVA
Hydantoin 5-propionic
Phenylpropionylglycine
Vanillyllactic
Vanillactic
Suberylglycine
Vanillylpyruvic
N-Acetylvanilalanine
Hawkinsin
Tyrosinemia
Phenylketonuria
Alkaptonuria
Maple Syrup Urine Disease
Barth Syndrome
Costeff Syndrome
E3 Deficiency
MCAD
SBCAD
Beta-Ketothiolase Deficiency
Multiple Carboxylase Deficiency
SCAD
3HMG-CoA Synthase Deficiency
Dihydropyrimidine Dehydrogenase Deficiency
Neuroblastoma
Glutathione Synthetase Deficiency
SSADHD
Ethylmalonic Encephalopathy
MADD
Multiple Acyl-CoA Dehydrogenase Deficiency
Fumarase Deficiency
AADC
HIBCH
ECHS1
Dicarboxylic Aciduria
Canavan Disease
Hyperprolinemia Type II
Ornithine Transcarbamylase Deficiency
OTC
Aminoacylase Deficiency
Acids
Urine
1. Patient's age is required.
2. Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
Supplies: Urine Tubes, 10 mL (T068)
Collection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic, 10-mL urine tube
Specimen Volume: 10 mL
Pediatric: If insufficient collection volume, submit as much specimen as possible in a single container; the laboratory will determine if volume is sufficient for testing.
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
4 mL
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Urine | Frozen (preferred) | 416 days | |
Refrigerated | 14 days |
Diagnosis of inborn errors of metabolism
Organic acids occur as physiologic intermediates in a variety of metabolic pathways. Organic acidurias are a group of disorders in which one or more of these pathways are blocked, resulting in a deficiency of normal products and an abnormal accumulation of intermediate metabolites (organic acids) in the body. These excess metabolites are excreted in the urine.
The incidence of individual inborn errors of organic acid metabolism varies from 1 in 10,000 to greater than 1 in 1,000,000 live births. Collectively, their incidence approximates 1 in 3000 live births. This estimate, however, does not include other inborn errors of metabolism (ie, amino acid disorders, urea cycle disorders, congenital lactic acidemias) for which diagnosis and monitoring may require organic acid analysis. If all possible disease entities were included, the incidence of conditions where informative organic acid profiles could be detected in urine is likely to approach 1 in 1000 live births.
Organic acidurias typically present with either an acute life-threatening illness in early infancy or unexplained developmental delay with intercurrent episodes of metabolic decompensations in later childhood. A situation of severe and persistent metabolic acidosis of unexplained origin, elevated anion gap, and severe neurologic manifestations, such as seizures, should be considered strong diagnostic indicators of one of these diseases. The presence of ketonuria, occasionally massive, provides an important clue toward the recognition of disorders, especially in the neonatal period. Hyperammonemia, hypoglycemia, and lactic acidemia are frequent findings, especially during acute episodes of metabolic decompensations.
An interpretive report will be provided.
When no significant abnormalities are detected, the organic acid analysis is reported and interpreted in qualitative terms only. When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, and recommendations for additional biochemical testing, and in vitro confirmatory studies (enzyme assay, molecular analysis).
The diagnostic specificity of organic acid analysis under acute and asymptomatic conditions may vary considerably.
Informative profiles may not always be detected in disorders where the excretion of diagnostic metabolites is a reflection of the residual activity of the defective enzyme, the dietary load of precursors, and the anabolic/catabolic status of a patient.
In some cases, methods of higher specificity and sensitivity, such as acylcarnitine and acylglycine analysis, can effectively overcome the limitations of standard organic acid analysis for the investigation of patients who are not acutely ill.
1. Lehotay DC, Clarke JT. Organic acidurias and related abnormalities. Crit Rev Clin Lab Sci. 1995;32(4):377-429
2. Ferreira CR, van Karnebeek CDM. Inborn errors of metabolism. In: de Vries LS, Glass HC, eds. Neonatal Neurology. Elsevier; 2019:449-481. Handbook of Clinical Neurology. Vol 162
3. Chapman KA. Practical management of organic acidemias. Trans Sc Rare Dis. 2019;1-12. doi:10.3233/TRD-190039
A urine volume corresponding to 0.25 mg of creatinine is acidified and then extracted with ethyl acetate. After separation and evaporation of the solvent phase, the dry residue is sialylated and analyzed by capillary gas chromatography mass spectrometry. When indicated, oxidation of 2-keto acids is performed by reaction with hydroxylamine hydrate.(Sweetman L. Organic acid analysis. In: Hommes FA, ed. Techniques in Diagnostic Human Biochemical Genetics. Wiley-Liss; 1991:143-176; Hoffman GF, Feyh P. Organic acid analysis. In: Blau N, Duran M, Blaskovics ME, Gibson KM, eds. Physician's Guide to the Laboratory Diagnosis of Metabolic Diseases. Springer; 2003:27-44; Cowan T, Pasquali M. Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1143)
Monday through Saturday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
83919
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
OAU | Organic Acids Scrn, U | 49287-6 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
80619 | Organic Acids Scrn, U | 49287-6 |