Test Id : AAUCD
Amino Acids, Urea Cycle Disorders Panel, Plasma
Useful For
Suggests clinical disorders or settings where the test may be helpful
Follow-up of patients with urea cycle disorders
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Urea cycle disorders are a group of inherited disorders of nitrogen detoxification that result from defects in any of the enzymes involved in the urea cycle.
Disruption of the urea cycle can result in the accumulation of ammonia, which is toxic to the nervous system.
Highlights
Plasma amino acid analysis can be used to aid in the diagnosis of a urea cycle disorder as well as for follow-up of a known patient.
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
Arginase Deficiency
Arginine
Argininemia
Argininosuccinic Acid
Argininosuccinic Acid Lyase Deficiency
Argininosuccinic Aciduria
Carbamoyl Phosphate Synthetase (CPS) Deficiency
Citrulline
Citrullinemia
CPS (Carbamoyl Phosphate Synthetase)
Glutamine
N-acetyl Glutamate Synthase (NAGS) Deficiency
NAGS (N-acetyl Glutamate Synthetase)
Ornithine
Ornithine Transcarbamylase (OTC) Deficiency
OTC (Ornithine Transcarbamylase)
UCD (Urea Cycle Disorder)
Urea Cycle Disorder (UCD)
Argininosuccinic Acid Synthetase Deficiency
Gyrate atrophy
Ornithine Aminotransferase (OAT) Deficiency
Specimen Type
Describes the specimen type validated for testing
Plasma
Ordering Guidance
Body fluids are not acceptable specimens for this test.
For testing on urine specimens, order AAPD / Amino Acids, Quantitative, Random, Urine.
For testing on spinal fluid specimens, order AACSF / Amino Acids, Quantitative, Spinal Fluid.
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
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Patient Preparation:
Fasting: 4 hours, required; infants should have specimen collected before next feeding (2-3 hours without total parenteral nutrition if possible)
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Green top (sodium heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Collect specimen and place on wet ice. Note: Thrombin-activated tubes should not be used for collection.
2. Centrifuge immediately or within 4 hours of collection if the specimen is kept at refrigerated temperature.
3. Being careful to ensure that no buffy coat is transferred, aliquot plasma into a plastic vial and freeze.
Forms
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.
0.3 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
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 |
|---|---|---|---|
| Plasma | Frozen | 14 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Follow-up of patients with urea cycle disorders
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Urea cycle disorders are a group of inherited disorders of nitrogen detoxification that result from defects in any of the enzymes involved in the urea cycle.
Disruption of the urea cycle can result in the accumulation of ammonia, which is toxic to the nervous system.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urea cycle disorders (UCD) are a group of inherited disorders of nitrogen detoxification that result when any of the enzymes in the urea cycle (carbamoylphosphate synthetase I [CPS I], ornithine transcarbamylase [OTC], argininosuccinic acid synthetase, argininosuccinic acid lyase, arginase, or the cofactor producer, N-acetyl glutamate synthetase [NAGS]), have deficient or reduced activity. The role of the urea cycle is to metabolize and clear waste nitrogen, and defects in any of the steps of the pathway can result in an accumulation of ammonia, which can be toxic to the nervous system. The urea cycle is also responsible for endogenous production of the amino acids citrulline, ornithine, and arginine. Infants with a complete urea cycle enzyme deficiency typically appear normal at birth but, as ammonia levels rise, present during the neonatal period with lethargy, seizures, hyper- or hypoventilation, and, ultimately, coma or death. Individuals with partial enzyme deficiency may present later in life, typically following an acute illness or other stressors. Symptoms may be less severe and may present with episodes of psychosis, lethargy, cyclical vomiting, and behavioral abnormalities. Patients with impaired ornithine metabolism due to ornithine aminotransferase deficiency may present with childhood-onset myopia progressing to vision loss in the 4th to 6th decades of life. Patients may or may not have accompanying hyperammonemia but display marked elevations in plasma ornithine.
All UCD are inherited autosomal recessively, with the exception of OTC deficiency, which is X-linked. UCD may be suspected in cases with elevated ammonia, normal anion gap, and a normal glucose. Plasma amino acids can be used to aid in the diagnosis of UCD and may aid in monitoring treatment effectiveness. Measurement of urinary orotic acid, enzyme activity (CPS I, OTC, or NAGS), and molecular genetic testing can help to distinguish the conditions and allows for diagnostic confirmation.
Acute treatment for UCD consists of dialysis and administration of nitrogen scavenger drugs to reduce ammonia concentration. Chronic management typically involves restriction of dietary protein with essential amino acid supplementation. More recently, orthotopic liver transplantation has been used with success in treating some patients.
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.
Glutamine
<24 months: 356-857 nmol/mL
2-17 years: 353-790 nmol/mL
> or =18 years: 447-774 nmol/mL
Ornithine
<24 months: 32-171 nmol/mL
2-17 years: 32-148 nmol/mL
> or =18 years: 39-154 nmol/mL
Citrulline
<24 months: 8-42 nmol/mL
2-17 years: 12-44 nmol/mL
> or =18 years: 18-57 nmol/mL
Arginine
<24 months: 28-164 nmol/mL
2-17 years: 28-156 nmol/mL
> or =18 years: 45-144 nmol/mL
Argininosuccinic Acid
<5 nmol/mL
Reference value applies to all ages.
Interpretation
Provides information to assist in interpretation of the test results
The quantitative results of glutamine, ornithine, citrulline, arginine, and argininosuccinic acid with age-dependent reference values are reported without added interpretation. When applicable, reports of abnormal results may contain an interpretation based on available clinical interpretation.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Reference values are for fasting patients.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Brusilow SW, Horwich AL. Urea cycle enzymes. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA. eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw Hill; 2019. Accessed April 22, 2024. https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225084071
2. Haberle J, Burlina A, Chakrapani A, et al. Suggested guidelines for diagnosis and management of urea cycle disorders: First revision. J Inherit Metab Dis. 2019;42(6):1192-1230. doi:10.1002/jimd.12100
3. Valle D, Simell O. The Hyperornithinemias. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA. eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw Hill; 2019. Accessed April 22, 2024. https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225083672
4. Ah Mew N, McCarter R, Izem R, et al. Comparing Treatment Options for Urea Cycle Disorders. Washington (DC): Patient-Centered Outcomes Research Institute (PCORI); December 2020
Method Description
Describes how the test is performed and provides a method-specific reference
Quantitative analysis of amino acids is performed by liquid chromatography tandem mass spectrometry. Patient samples are combined with isotopically labeled internal standard. Following protein precipitation, the supernatant is subjected to hydrophilic-interaction liquid chromatography for the separation of isomers with MS/MS detection of the underivatized amino acids.(Unpublished Mayo method)
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.
Monday through Friday
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.
82136
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 |
|---|---|---|
| AAUCD | Amino Acid, Urea Cycle Panel, P | 100368-0 |
| 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.
|
|---|---|---|
| 32440 | Glutamine | 20643-3 |
| 32441 | Citrulline | 20640-9 |
| 32442 | Argininosuccinic Acid | 32227-1 |
| 32443 | Arginine | 20637-5 |
| 32444 | Ornithine | 20652-4 |
| 32445 | Interpretation (AAUCD) | 49247-0 |