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Lab Dept:
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Chemistry
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Test Name:
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LONG CHAIN FATTY ACIDS
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General Information
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Lab Order Codes:
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LFAT
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Synonyms:
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Fatty Acid Profile, Peroxisomal (C22-C26), Serum; Phytanic Acid; Pristanic Acid; Very Long Chain Fatty Acids
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CPT Codes:
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82726 – Very long chain fatty acids
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Test Includes:
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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
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Logistics
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Test Indications:
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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.
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Lab Testing Sections:
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Chemistry – Sendouts
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Referred to:
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Mayo Medical Laboratories (Test# 81369)
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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3 - 7 days, test set up Monday - Friday
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Special Instructions:
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Include information regarding treatment, family history and tentative diagnosis. Refer to Patient Preparation.
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Specimen
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Specimen Type:
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Blood
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Container:
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Red top tube
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Draw Volume:
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1.5 mL blood
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Processed Volume:
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0.5 mL (Minimum: 0.15 mL) serum
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Collection:
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Routine venipuncture
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Special Processing:
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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.
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Patient Preparation:
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Patient must not consume any alcohol for 24 hours before the specimen is drawn. Overnight (12 - 14 hour) fast recommended.
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Sample Rejection:
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Samples other than serum or plasma (EDTA or heparin); warm specimens; mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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C22:0
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≤96.3 nmol/mL
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C24:0
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≤91.4 nmol/mL
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C26:0
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≤1.30 nmol/mL
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C24:0/C22:0 Ratio
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≤1.39 ratio
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C26:0/C22:0 Ratio
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≤0.023 ratio
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Pristanic Acid (nmol/mL):
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0 – 4 months
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≤0.60
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5 –8 months
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≤0.84
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9 – 12 months
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≤0.77
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13 – 23 months
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≤1.47
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≥24 months
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≤2.98
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Phytanic Acid (nmol/mL):
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0 – 4 months
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≤5.28
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5 –8 months
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≤5.70
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9 – 12 months
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≤4.40
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13 – 23 months
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≤8.62
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≥24 months
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≤9.88
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Pristanic/Phytanic Acid Ratio:
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0 – 4 months
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≤0.35
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5 –8 months
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≤0.28
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9 – 12 months
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≤0.23
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13 – 23 months
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≤0.24
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≥24 months
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≤0.39
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Critical Values:
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N/A
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Limitations:
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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.
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Methodology:
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Gas Chromatography/Mass Spectrometry (GC-MS), Stable Isotope Dilution Analysis
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References:
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Mayo Medical Laboratories September 2012
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Updates:
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9/27/2012: EDTA and Heparin removed as alternated tube types.
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