Test Id : OROT
Orotic Acid, Random, Urine
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation of the differential diagnosis of hyperammonemia and hereditary orotic aciduria
Sensitive indicator of ornithine transcarbamylase (OTC) activity after administration of allopurinol or a protein load to identify OTC carriers
Method Name
A short description of the method used to perform the test
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Cit I
Citrullinemia I
HHH
LPI
UMPS
Urea Cycle Disorder (UCD)
OTC (Ornithine Transcarbamylase)
ASA (Aspirin)
Argininosuccinic Aciduria
Hereditary Orotic Aciduria
Hyperornithinemia, Hyperammonemia, Homocitrullinuria Syndrome
Lysinuric Protein Intolerance
Ornithine Transcarbamylase Deficiency
Uridine Monophosphate Synthase Deficiency
Argininosuccinate lyase deficiency
Argininosuccinic acid lyase deficiency
Argininosuccinate synthetase deficiency
Specimen Type
Describes the specimen type validated for testing
Urine
Necessary Information
Patient's age is required.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Supplies: Urine Tubes, 10 mL (T068)
Container/Tube: Plastic, 10-mL urine tube
Specimen Volume: 3 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative needed.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
2 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Frozen | 90 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation of the differential diagnosis of hyperammonemia and hereditary orotic aciduria
Sensitive indicator of ornithine transcarbamylase (OTC) activity after administration of allopurinol or a protein load to identify OTC carriers
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urinary excretion of orotic acid, an intermediate in pyrimidine biosynthesis, is increased in many urea cycle disorders and in a number of other disorders involving the metabolism of arginine. The determination of orotic acid can be useful to distinguish between various causes of elevated ammonia (hyperammonemia). Hyperammonemia is characteristic of all urea cycle disorders, but orotic acid is only elevated in some, including ornithine transcarbamylase (OTC) deficiency, citrullinemia, and argininosuccinic aciduria. Orotic acid is also elevated in the transport defects of dibasic amino acids (lysinuric protein intolerance and hyperornithinemia, hyperammonemia, and homocitrullinuria [HHH] syndrome) and is greatly elevated in patients with hereditary orotic aciduria (uridine monophosphate synthase [UMPS] deficiency).
Ornithine transcarbamylase deficiency is an X-linked urea cycle disorder that affects patients to varying degrees based on their sex and severity of molecular OTC variant. It is thought to be the most common urea cycle disorder, with an estimated incidence of 1:56,000. In OTC deficiency, carbamoyl phosphate accumulates and is alternatively metabolized to orotic acid. Allopurinol inhibits orotidine monophosphate decarboxylase and, when given to OTC carriers (who may have normal orotic acid excretion), can cause increased excretion of orotic acid. When orotic acid is measured after a protein load or administration of allopurinol, its excretion is a very sensitive indicator of OTC activity. A carefully monitored allopurinol challenge followed by several determinations of a patient's orotic acid excretion can be useful to identify OTC carriers, as approximately 5% to 10% of OTC variant are not detectable by current molecular genetic testing methods.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
< or =6 years: < or =4 mmol/mol creatinine
7-18 years: < or =3 mmol/mol creatinine
> or =19 years: 5 mmol/mol creatinine
Interpretation
Provides information to assist in interpretation of the test results
The value for the orotic acid concentration is reported. The
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Pregnant women will normally excrete up to twice the upper limit of the adult reference range.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Singh RH, Rhead WJ, Smith W, et al. Nutritional management of urea cycle disorders. Crit Care Clin. 2005;21(4 Suppl):S27-35
2. Lee B, Singh RH, Rhead WJ, et al. Considerations in the difficult-to-manage urea cycle disorder patient. Crit Care Clin. 2005;21(4 Suppl):S19-25
3. Brusilow SW, Horwich AL. Urea cycle enzymes. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed February 25, 2025. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225084071
4. Webster DR, Becroft DO, van Gennip AH, Van Kuilenburg AP. Hereditary orotic aciduria and other disorders of pyrimidine metabolism. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease., McGraw-Hill; 2019. Accessed February 25, 2025. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225090376
5. Ah Mew N, Simpson KL, Gropman AL, Lanpher BC, Chapman KA, Summar, ML. Urea cycle disorders overview. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2003. Updated May 26, 2022. Accessed February 25, 2025. Available at www.ncbi.nlm.nih.gov/books/NBK1217
Method Description
Describes how the test is performed and provides a method-specific reference
Diluted, filtered urine is mixed with an internal standard mixture and analyzed for orotic acid by liquid chromatography-tandem mass spectrometry. The ratio of the extracted peak area of orotic acid to the added internal standard is used to calculate the concentration present in the sample.(la Marca G, Casetta B, Malvagia S, et al. Implementing tandem mass spectrometry as a routine tool for characterizing the complete purine and pyrimidine metabolic profile in urine samples. J Mass Spectrom. 2006;41[11]:1442-1452; Monostori P, Klinke G, Hauke J, et al. Extended diagnosis of purine and pyrimidine disorders from urine: LC MS/MS assay development and clinical validation. PLoS One. 2019;14[2]:e0212458. doi:10.1371/journal.pone.0212458)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Tuesday, Thursday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
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.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83921
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| OROT | Orotic Acid, U | 17869-9 |
| 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.
|
|---|---|---|
| 8905 | Orotic Acid, U | 17869-9 |