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Epic Code LAB834 Organic Acids Screen, Random, Urine

Additional Codes

Mayo Code: OAU

Interface Order Alias: 10442

Cerner: 4165

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosis of inborn errors of metabolism

Specimen Type

Urine


Necessary Information


1. Patient's age is required.

2. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.



Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

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.


Specimen Minimum Volume

4 mL

Highlights

The urine organic acids (OAU) 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.

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen (preferred) 416 days
  Refrigerated  14 days

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Cautions

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 non-acutely ill patients.

Clinical Information

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 also 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.

Method Name

Gas Chromatography-Mass Spectrometry (GC-MS)

Report Available

3 to 6 days

Reporting Name

Organic Acids Scrn, U

Reference Values

An interpretive report will be provided.

Interpretation

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).

Method Description

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)

Day(s) Performed

Monday through Saturday

Clinical Reference

1. Lehotay DC, Clarke JT: Organic acidurias and related abnormalities. Crit Rev Clin Lab Sci. 1995;32:377-429

2. Seashore MR: The Organic Acidemias: An Overview. January 2007. Accessed February 10, 2020. Available at www.researchgate.net/publication/221964037_The_Organic_Acidemias_An_Overview

3. Chapman KA. Practical management of organic acidemias. Trans Sc Rare Dis. 2019;1-12. doi: 10.3233/TRD-190039

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83919

LOINC Code Information

Test ID Test Order Name Order LOINC Value
OAU Organic Acids Scrn, U 49287-6

 

Result ID Test Result Name Result LOINC Value
80619 Organic Acids Scrn, U 49287-6