Fatty Acid Profile, Peroxisomal (POX)

Test Code: FAPPXSO

Overview
Ordering
Specimen
Performing
Clinical/Interpretive
Contacts
Coding

Synonyms/Keywords

Ref Lab Code: 81369, 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

Aid in the assessment of peroxisomal function

Specimen Requirements

Fasting Required	Specimen Type	Preferred Container/Tube	Acceptable Container/Tube	Specimen Volume	Specimen Minimum Volume (allows for 1 repeat)	Pediatric Minimum Volume (no repeat)
Yes	Serum	Red Top Tube (RTT)	Serum Separator Tube (SST)	0.5 mL	0.15 mL

Collection Processing Instructions

1. Fasting-overnight (12-14 hours).

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

3. Spin down within 45 minutes of draw.

4. Submit sample in a plastic vial.

Additional Information:

1. Patient's age is required.

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

Specimen Stability Information

Specimen Type	Temperature	Time
Serum	Frozen (preferred)	90 days
	Refrigerated	24 hours

Rejection Criteria

Gross lipemia

Performing Laboratory Information

Performing Location	Day(s) Test Performed	Analytical Time	Methodology/Instrumentation
Mayo Medical Laboratories	Monday through Friday	4 days (not reported on Saturday or Sunday)	Gas Chromatography-Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis

Reference Lab

Mayo Clinic Laboratories

Test Information

Includes measurements of very long chain fatty acids, Pristanic acid, Phytanic acid, Pristanic / Phytanic acid ratio.

Reference Range Information

See report

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, serum 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 genetic or nongenetic condition. Additional confirmatory testing would be required.

Outreach CPTs

CPT	Modifier (if needed)	Quantity	Description	Comments
82726

Synonyms/Keywords

Ordering Applications

Ordering Application	Description

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