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HelpTest Code FAPOX Fatty Acid Profile, Peroxisomal (C22-C26), Serum
Reporting Name
Fatty Acid Profile, Peroxisomal, SUseful For
Evaluating patients with possible peroxisomal disorders, single-enzyme defects of peroxisomal metabolism such as X-linked adrenoleukodystrophy or peroxisomal biogenesis disorders (Zellweger syndrome spectrum) using serum specimens
Aiding in the assessment of peroxisomal function
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumNecessary Information
1. Patient's age and sex is required.
2. Include information regarding treatment, family history, and tentative diagnosis.
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.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial.
Specimen Minimum Volume
0.15 mL
Testing Algorithm
The following algorithms are available in Special Instructions:
-Newborn Screen Follow-up for X-Linked Adrenoleukodystrophy
-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
For more information, see Newborn Screening Act Sheet X-Linked Adrenoleukodystrophy: Increased Very Long Chain Fatty Acids in Special Instructions.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 92 days | |
| Refrigerated | 15 days |
Special Instructions
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
Day(s) Performed
Monday through Friday
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
82726
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| POX | Fatty Acid Profile, Peroxisomal, S | 43677-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 81369 | C22:0 | 30194-5 |
| 7143 | C24:0 | 30195-2 |
| 7137 | C26:0 | 30197-8 |
| 7138 | C24:0/C22:0 | 30196-0 |
| 7139 | C26:0/C22:0 | 30198-6 |
| 7140 | Pristanic Acid | 22761-1 |
| 7141 | Phytanic Acid | 22671-2 |
| 7142 | Pristanic/Phytanic | 30550-8 |
| 7144 | Comment | 48767-8 |
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;45:100-110
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
Method Description
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)
Report Available
2 to 5 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Method Name
Gas Chromatography-Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis
Forms
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.