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Lab Dept:
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Chemistry
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Test Name:
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CARNITINE, TOTAL AND FREE
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General Information
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Lab Order Codes:
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CARN
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Synonyms:
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L-Carnitine
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CPT Codes:
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82379 – Carnitine (total and free), quantitative, each specimen
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Test Includes:
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Total carnitine (TC), Free carnitine (FC), Acylcarnitine (AC) Range and AC/FC Ratio
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Logistics
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Test Indications:
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Evaluation of patients with a clinical suspicion of a wide range of inborn errors of metabolism, especially organic acidemias and fatty acid oxidation disorders including primary carnitine deficiency.
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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# 60449)
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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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2 - 5 days, performed Monday - Friday
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Special Instructions:
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N/A
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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, plain, no gel tubes
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Draw Volume:
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1.5 mL (Minimum: 0.6 mL) blood
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Processed Volume:
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0.5 mL (Minimum: 0.2 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 and remove serum aliquot into a screw-capped round bottom plastic vial. Store and shop at frozen temperatures. Indicate on label “serum”. This assay must be aliquoted into a separate vial and frozen. It should not be combined with other testing.
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Patient Preparation:
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None
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Sample Rejection:
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Specimens other than serum, warm specimens, mislabeled or unlabeled specimens
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Interpretive
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Reference Ranges:
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Age
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Total Carnitine(TC) Range nmol/mL
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Free Carnitine (FC) Range nmol/mL
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Acylcarnitine (AC) Range nmol/mL
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AC/FC Ratio
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1 day
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23 – 68
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12 – 36
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7 – 37
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0.4 – 1.7
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2 - 7 days
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17 – 41
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10 – 21
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3 – 24
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0.2 – 1.4
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8 - 31 days
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19 – 59
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12 – 46
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4 – 15
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0.1 – 0.7
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32 days – 12 months
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38 – 68
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27 – 49
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7 – 19
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0.2 – 0.5
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13 months – 6 years
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35 – 84
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24 – 63
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4 – 28
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0.1 – 0.8
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7 - 10 years
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28 – 83
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22 – 66
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3 – 32
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0.1 – 0.9
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11 - 17 years
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34 – 77
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22 – 65
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4 – 29
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0.1 – 0.9
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≥18 years
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34 – 78
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25 – 54
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5 – 30
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0.1 – 0.8
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Table used with permission of Schmidt-Sommerfeld E, Werner E, Penn D: Carnitine plasma concentrations in 353 metabolically healthy children. Eur J Pediatr 147:356-360, 1988 and the European Journal of Pediatrics, Springer-Verlag, New York, Inc., Secaucus, NJ
Interpretation: When abnormal results are detected, a detailed interpretation is given, including an overview of the results and their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.
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Critical Values:
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N/A
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Limitations:
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Determination of urine carnitine concentration concurrently with serum concentration is recommended.
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Methodology:
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Tandem Mass Spectrometry (MS/MS)
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References:
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Mayo Medical Laboratories Web Page (October 2010)
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Updates:
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10/12/2010: Units change, previously reported as umol/L.
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