Determination Of The Reference Range Of Blood Spot Free Carnitine And Acylcarnitines In Healthy Children By Tandem Mass

ObjectiveTo establish a method for carnitine analysis in dry blood filter paper by tandem mass spectrometry for 0～13 years old children. In this study, we evaluated the variations in free carnitine and acylcarnitines concentrations with age, supplied normal reference range for clinic diagnosis.Methods5 mm diameter of dry blood spots were punched and extracted by methanol solution with stable isotope labeled internal standards , then filtered and analyzed by tandem mass spectrometry.Sensitivity and specificity were evaluated by the quality control samples supplied by CDC of United States.Filter-paper blood spots were collected from 277 healthy individuals over a period of 3 months, divided into six age groups to analysis, including:1–28 days(group 1), 1–6 months(group 2),7–12 months(group 3), 13 months–3 years(group 4), 4–6 years(group 5)and 7–13 years(group 6). The concentration of free carnitine and acylcarnitines were made statistic to get normal reference range .ResultsThe intraassay CVs of this method were 1% -13% ,The interassay CVs were1% -16%. The linearity of free carnitine and acylcarnitines were enough to the requitement of clinic diagnosis .Long chain carnitines was significantly higher in newborns than in older children (P <0.05), but the concentrations of several short chain acylcarnitines(C3,C4,C5,C6) tended to be no significantly difference. By this method,we identified one patient withβ-oxidation disorders deficiency which proved the method is specificity and sensitivity.ConclusionsThe precision and linearity of the method are satisfied for free carnitine and acylcarnitines analysis. The age-related reference values are useful in the diagnosis and management of inherited errors of metabolism.