Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

LONG CHAIN FATTY ACIDS

General Information

Lab Order Codes:

LFAT

Synonyms:

Fatty Acid Profile, Peroxisomal (C22-C26), Serum; Phytanic Acid; Pristanic Acid; Very Long Chain Fatty Acids

CPT Codes:

82726 – Very long chain fatty acids

Test Includes:

C22:0, C24:0, C26:0, C24:0/C22:0 Ratio C26:0/C22:0 Ratio, Pristanic Acid, Phytanic Acid and Pristanic/Phytanic Acid Ratio

Logistics

Test Indications:

Investigation of patients with possible peroxisomal disorders, including (X-ALD) and Refsum’s disease. Diagnosis of Refsum’s disease and to aid in the assessment of peroxisomal function.

Lab Testing Sections:

Chemistry – Sendouts

Referred to:

Mayo Medical Laboratories (MML Test: 81369/POX)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

3 - 7 days, test set up Monday - Friday

Special Instructions:

Include information regarding treatment, family history and tentative diagnosis. Refer to Patient Preparation.

Specimen

Specimen Type:

Blood

Container:

Red top tube

Draw Volume:

1.5 mL (Minimum: 0.5 mL) blood

Processed Volume:

0.5 mL (Minimum: 0.15 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab staff: Centrifuge specimen within 45 minutes of collection, remove serum aliquot into a screw-capped round bottom plastic vial. Store and ship at frozen temperatures. Include information regarding treatment, family history, and tentative diagnosis. Must include patient’s age.

Patient Preparation:

Patient must not consume any alcohol for 24 hours before the specimen is drawn. Overnight (12 - 14 hour) fast recommended.

Sample Rejection:

Samples other than serum or plasma (EDTA or heparin); warm specimens; mislabeled or unlabeled specimens

Interpretive

Reference Range:

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 ratio

C26:0/C22:0 Ratio

≤0.023 ratio

Pristanic Acid (nmol/mL):

0 – 4 months

≤0.60

5 –8 months

≤0.84

9 – 12 months

≤0.77

13 – 23 months

≤1.47

≥24 months

≤2.98

Phytanic Acid (nmol/mL):

0 – 4 months

≤5.28

5 –8 months

≤5.70

9 – 12 months

≤4.40

13 – 23 months

≤8.62

≥24 months

≤9.88

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

Critical Values:

N/A

Limitations:

In rare instances, patients with X-ALD may have only minimally elevated values, 15-20% of women heterozygous for X-ALD have normal plasma VLCFA levels.

Dietary treatment (Lorenzo’s oil, ketogenic diet) and drugs (Lovastatin) could result in values of difficult interpretation.

Methodology:

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

References:

Mayo Medical Laboratories September 2012

Updates:

9/27/2012: EDTA and Heparin removed as alternated tube types.



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