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HelpTest Code POXP Fatty Acid Profile, Peroxisomal (C22-C26), Plasma
Additional Codes
Aliases:
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
Useful For
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
Method Name
Gas Chromatography Mass Spectrometry (GC-MS)
Reporting Name
Fatty Acid Profile, Peroxisomal,PSpecimen Type
PlasmaSpecimen Minimum Volume
0.15 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma | Frozen (preferred) | 92 days | |
| Refrigerated | 15 days |
Reference Values
C22:0
≤96.3 nmol/mL
C24:0
≤91.4 nmol/mL
C26:0
≤1.30 nmol/mL
C24:0/C22:0 RATIO
≤1.39
C26:0/C22:0 RATIO
≤0.023
PRISTANIC ACID
0-4 months: ≤0.60 nmol/mL
5-8 months: ≤0.84 nmol/mL
9-12 months: ≤0.77 nmol/mL
13-23 months: ≤1.47 nmol/mL
≥24 months: ≤2.98 nmol/mL
PHYTANIC ACID
0-4 months: ≤5.28 nmol/mL
5-8 months: ≤5.70 nmol/mL
9-12 months: ≤4.40 nmol/mL
13-23 months: ≤8.62 nmol/mL
≥24 months: ≤9.88 nmol/mL
PRISTANIC/PHYTANIC ACID RATIO
0-4 months: ≤0.35
5-8 months: ≤0.28
9-12 months: ≤0.23
13-23 months: ≤0.24
≥24 months: ≤0.39
Interpretation
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, the calculated value of a discriminating function that more accurately segregates hemizygous individuals from normal controls is included in the report.
Positive test results could be due to a genetic or nongenetic condition. Additional confirmatory testing would be required to differentiate between these causes.
Clinical Reference
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(1):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;1863(5):922-933. doi:10.1016/j.bbamcr.2015.11.015
Day(s) Performed
Monday through Friday
Report Available
3 to 5 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
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
82726
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| POXP | Fatty Acid Profile, Peroxisomal,P | 43677-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 36641 | C22:0 | 30194-5 |
| 36642 | C24:0 | 30195-2 |
| 36643 | C26:0 | 30197-8 |
| 36644 | C24:0/C22:0 | 30196-0 |
| 36645 | C26:0/C22:0 | 30198-6 |
| 36646 | Pristanic Acid | 22761-1 |
| 36647 | Phytanic Acid | 22671-2 |
| 36648 | Pristanic/Phytanic | 30550-8 |
| 36649 | Interpretation (POXP) | 59462-2 |
Testing Algorithm
For more information see:
-Newborn Screen Follow-up for X-Linked Adrenoleukodystrophy
-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
-Newborn Screening Act Sheet X-linked Adrenoleukodystrophy: Increased Very Long Chain Fatty Acids
Special Instructions
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.
Necessary Information
1. Patient's age and sex 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.
Specimen Required
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.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
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.