Test Catalog

Test Id : POXP

Fatty Acid Profile, Peroxisomal (C22-C26), Plasma

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with possible peroxisomal disorders, including peroxisomal biogenesis disorders, X-linked adrenoleukodystrophy, and Refsum disease using plasma specimens

 

Aiding in the assessment of peroxisomal function

Highlights

This test analyzes very long-chain fatty acids as well as pristanic and phytanic acid to aid in diagnosis of peroxisomal biogenesis disorders, X-linked adrenoleukodystrophy (X-ALD), and Refsum disease.

 

Reports include concentrations of C22:0, C24:0, C26:0 species, phytanic acid and pristanic acid, and calculated C24:0/C22:0, C26:0/C22:0, and phytanic acid:pristanic acid ratios.

 

This test is also appropriate for follow-up of an abnormal newborn screen for X-ALD.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Gas Chromatography-Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Fatty Acid Profile, Peroxisomal,P

Aliases
Lists additional common names for a test, as an aid in searching

Adrenoleukodystrophy (ALD)

Adrenomyeloneuropathy

C22-C26, Fatty Acid Profile, Peroxisomal

Cerebrohepatorenal Syndrome

Long-Chain Fatty Acids (LCFA)

Peroxisomal, Fatty Acid Profile

Phytanic Acid

Phytanic Acid Oxidase Deficiency

Pristanic Acid

Refsum Disease

Very Long Chain Fatty Acids (VLCFA)

X-ALD (X-Linked Adrenoleukodystrophy)

X-Linked Adrenoleukodystrophy (X-ALD)

Zellweger Syndrome

ZSD

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type
Describes the specimen type validated for testing

Plasma

Necessary Information

1. Patient's age and sex is required.

2. Include information regarding treatment, family history, and tentative diagnosis.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation:

1. Fasting-overnight (12-14 hours). If fasting not possible for babies or infants, collect specimen prior to next feeding.

2. Patient must not consume any alcohol for 24 hours before the specimen is collected.

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA) or green top (lithium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot plasma into plastic vial.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.15 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK
Gross lipemia Reject
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 (preferred) 92 days
Refrigerated 15 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with possible peroxisomal disorders, including peroxisomal biogenesis disorders, X-linked adrenoleukodystrophy, and Refsum disease using plasma specimens

 

Aiding in the assessment of peroxisomal function

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Peroxisomes are organelles present in all human cells except mature erythrocytes. They carry out essential metabolic functions including beta-oxidation of very long-chain fatty acids (VLCFA), alpha-oxidation of phytanic acid, and biosynthesis of plasmalogen and bile acids. Peroxisomal disorders include disorders of peroxisomal biogenesis with defective assembly of the entire organelle and single peroxisomal enzyme/transporter defects where the organelle is intact, but a specific function is disrupted. Peroxisomal beta-oxidation of VLCFA is impaired in all disorders of peroxisomal biogenesis and in selected single enzyme deficiencies, particularly X-linked adrenoleukodystrophy (X-ALD), resulting in elevated concentrations of VLCFA in plasma or serum.

 

Peroxisomal biogenesis disorders (PBD) include the Zellweger syndrome spectrum disorders, which are clinically diverse and range in severity from neonatal lethal (Zellweger syndrome) to more variable clinical courses in neonatal adrenoleukodystrophy and infantile Refsum disease. Affected children typically have hypotonia, poor feeding, distinctive facial features, seizures, and liver dysfunction. Other features can include retinal dystrophy, hearing loss, developmental delays, and bleeding episodes. Rhizomelic chondrodysplasia punctata is another PBD. It is characterized by rhizomelic shortening, chondrodysplasia punctata, cataracts, intellectual disability, and seizures, although it can have a milder phenotype with only cataracts and chondrodysplasia. The typical biochemical profile shows normal VLCFA and elevated phytanic acid.

 

X-ALD is a neurologic disorder affecting the white matter and adrenal cortex. It can present between ages 4 and 8 years as a childhood cerebral form with behavioral and cognitive changes, associated with neurologic decline. Other forms include an "Addison disease only" phenotype with adrenocortical insufficiency without initial neurologic abnormality and adrenomyeloneuropathy associated with later-onset progressive paraparesis. X-ALD is an X-linked condition that primarily affects male patients; however, some female patients who are carriers can develop later-onset neurologic manifestations. In 2016, X-ALD was added to the US Recommended Uniform Screening Panel, a list of conditions that are nationally recommended for newborn screening by the Secretary's Advisory Committee on Heritable Disorders in Newborns and Children.

 

Refsum disease is a peroxisomal disorder characterized by anosmia, retinitis pigmentosa, neuropathy, deafness, ataxia, ichthyosis, and cardiac abnormalities. The classic biochemical profile of Refsum disease is an elevated plasma or serum phytanic acid level.

 

Biochemical abnormalities in peroxisomal disorders include accumulations of VLCFA, phytanic, and pristanic acid. The differential diagnosis of these disorders is based on recognition of clinical phenotypes combined with a series of biochemical tests to assess peroxisomal function and structure. These include measurements and ratios of VLCFA, pipecolic acid (PIPA / Pipecolic Acid, Serum; PIPU / Pipecolic Acid, Random, Urine), phytanic acid and its metabolite pristanic acid. In addition, confirmatory testing for X-ALD (XALDZ / X-Linked Adrenoleukodystrophy, Full Gene Analysis, Varies) via molecular genetic analysis is available.

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.

C22:0

< or =96.3 nmol/mL

 

C24:0

< or =91.4 nmol/mL

 

C26:0

< or =1.30 nmol/mL

 

C24:0/C22:0 RATIO

< or =1.39

 

C26:0/C22:0 RATIO

< or =0.023

 

PRISTANIC ACID

0-4 months: < or =0.60 nmol/mL

5-8 months: < or =0.84 nmol/mL

9-12 months: < or =0.77 nmol/mL

13-23 months: < or =1.47 nmol/mL

> or =24 months: < or =2.98 nmol/mL

 

PHYTANIC ACID

0-4 months: < or =5.28 nmol/mL

5-8 months: < or =5.70 nmol/mL

9-12 months: < or =4.40 nmol/mL

13-23 months: < or =8.62 nmol/mL

> or =24 months: < or =9.88 nmol/mL

 

PRISTANIC/PHYTANIC ACID RATIO

0-4 months: < or =0.35

5-8 months: < or =0.28

9-12 months: < or =0.23

13-23 months: < or =0.24

> or =24 months: < or =0.39

Interpretation
Provides information to assist in interpretation of the test results

Reports include concentrations of C22:0, C24:0, C26:0 species, phytanic acid and pristanic acid, and calculated C24:0/C22:0, C26:0/C22:0, and phytanic acid:pristanic acid ratios. When no significant abnormalities are detected, a simple descriptive interpretation is provided.

 

A profile of elevated phytanic acid, low-normal pristanic acid, and normal very long-chain fatty acids is suggestive of Refsum disease (phytanic acid oxidase deficiency); however, phytanic acid concentration may also be increased in disorders of peroxisomal biogenesis and should be considered in the differential diagnosis of peroxisomal disorders.

 

If results are suggestive of hemizygosity for X-linked adrenoleukodystrophy, we also include the calculated value of a discriminating function used to more accurately segregate hemizygous individuals from normal controls.

 

Positive test results could be due to a genetic or nongenetic condition. Additional confirmatory testing would be required to differentiate between these causes.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

In rare instances, patients with X-linked adrenoleukodystrophy (X-ALD) may have only minimally elevated values; 15% to 20% of women heterozygous for X-ALD have normal plasma very long-chain fatty acid levels.

 

False-positive results may occur with nonfasting specimens.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Moser AB, Kreiter N, Bezman L, et al: Plasma very long chain fatty acid assay in 3,000 peroxisome disease patients and 29,000 controls. Ann Neurol. 1999;45:100-110

2. Turk BR, Theda C, Fatemi A, Moser AB: X-linked adrenoleukodystrophy: Pathology, pathophysiology, diagnostic testing, newborn screening and therapies. Int J Dev Neurosci. 2020;80(1):52-72. doi: 10.1002/jdn.10003

3. Waterham HR, Ferdinandusse S, Wanders RJA: Human disorders of peroxisome metabolism and biogenesis. Biochimica et Biophysica Acta. 2016 May;1863(5):922-933. doi: 10.1016/j.bbamcr.2015.11.015

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Acidic hydrolysis is followed by basic hydrolysis and reacidification. Hexane extraction then proceeds to derivatization with pentafluorobenzyl bromide (PFB). Separation and detection of PFB-esters is accomplished by capillary gas chromatography-mass spectrometry using electron capture ionization and selected negative ion monitoring. Quantitation is enhanced by the use of stable isotope-labeled internal standards.(Stellard F, ten Brink HJ, Kok RM, et al: Stable isotope dilution analysis of very long chain fatty acids in plasma, urine and amniotic fluid by electron capture negative ion mass fragmentography. Clin Chim Acta. 1990;192:133-144, Rattay TW, Rautenberg M, Sohn AS, et al: Defining diagnostic cutoffs in neurological patients for serum very long chain fatty acids (VLCFA) in genetically confirmed X-adrenoleukodystrophy. Sci Rep. 2020 Sep 15;10[1]:15093)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

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.

2 to 5 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 month

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

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 Regional Manager. 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. This test 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.

82726

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports