Biomarkers · Chemical
We have not added a physiological summary for this biomarker yet. Compare the commercial laboratory assays and population reference ranges below.
Check orderable catalog codes, specimen types, fasting requirements, and demographic reference ranges across laboratories.
Laboratory assay overview
Used in the diagnosis and monitoring of inherited disorders of fatty acid oxidation and organic acidurias. May be used as a follow-up test to some abnormal newborn screen results.
Labcorp test directory, test code 070228
Laboratory assay overview
Elevation of one or more acylcarnitines is diagnostic for an organic aciduria or a fatty disorder. A low carnitine level may mask a disease state.
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Quest Diagnostics test directory, test code 14531
Laboratory assay overview
A plasma acylcarnitine profile is one of the most powerful and accurate methods to diagnose inborn errors of fatty acid metabolism and organic acidemias. In newborn screening, newborns have sufficient free carnitine provided through the placenta from the mother to make acylcarnitine profiling alone sufficient to rule out these inborn errors. Unfortunately, after the newborn period, at the time of presentation and diagnosis, many patients with these disorders have become chronically depleted of free carnitine due to the inability to recycle esterified carnitine. In this situation, the acylcarnitine profile may be normal with all values in the lower end of the normal range despite the patient being affected with a disorder of fatty acid oxidation or an organic acidemia. Recently, we had just such a case with a patient known to have methylmalonic acidemia because of organic acid analysis who initially had a normal acylcarnitine profile. In such cases, a carnitine analysis would have shown extremely low free carnitine and very elevated carnitine esters and would have prompted carnitine supplementation of the patient followed by further periodic evaluations. As clinicians come to rely increasingly on acylcarnitine profiling to diagnose inborn errors of metabolism, it will be important to assay both carnitine (free and esterified) simultaneously with acylcarnitines for the initial evaluation of children for inborn errors of metabolism. This approach would prevent false negative results and false reassurance that could occur if acylcarnitines alone were ordered.
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Quest Diagnostics test directory, test code 15948
Laboratory assay overview
Comprehensive Fatty Acids (C8-C26), to evaluate patients for certain mitochondrial fatty acid oxidation defects, peroxisomal defects, and/or a full nutritional assessment. It can also be used to monitor patients receiving a special diet and/or fatty acid supplementation.
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Quest Diagnostics test directory, test code 17568
Laboratory assay overview
Mitochondrial Fatty Acids (C8-C18), to be used to evaluate patients for certain mitochondrial fatty acid oxidation defects as well as for monitoring of dietary therapy.
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Quest Diagnostics test directory, test code 94823
We compile every detail above directly from named laboratory directories and published clinical studies. Laboratories calculate standard reference intervals from the statistical distribution of tested populations for a specific assay method and demographic group, rather than setting universal optimal targets.
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