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Order Code POXP Fatty Acid Profile, Peroxisomal (C22-C26), Plasma

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,P

Specimen Type

Plasma

Specimen Minimum Volume

Plasma: 0.15 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Frozen (preferred) 92 days
  Refrigerated  15 days

Reject Due To

Gross hemolysis OK
Gross lipemia Reject
Gross icterus OK

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

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;10[1]:15093)

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

 

If the patient has abnormal newborn screening results for X-linked adrenoleukodystrophy, refer to the appropriate American College of Medical Genetics and Genomics Newborn Screening ACT Sheet.(1)

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: 12 hours, required; Infants and small children should have specimen collected just before next feeding/meal

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 plasma

Collection Instructions: Centrifuge and aliquot plasma into plastic vial.