ABSTRACT
Se han encontrado concentraciones anormales de carnitina en niños asociadas con deficiencias primaria y secundaria de carnitina, con disminución de las concentraciones en sangre y tejidos, así como niveles elevados en algunos errores innatos del metabolismo. El presente estudio tiene como objetivo la obtención de valores de referencia para carnitina libre y total en sangre de cordón umbilical, como herramienta en el diagnóstico temprano de errores innatos del metabolismo. Se analizaron mediante espectrometría de masas en tándem (MS/MS) 130 muestras de sangre de cordón umbilical de nacimientos con embarazos a término y peso normal al nacer (78 niños y 52 niñas) de una población colombiana. No se encontró diferencia estadísticamente significativa dependiendo del sexo del recién nacido. Reportamos valores de referencia para carnitina libre y total en sangre de cordón umbilical de 18,5+/-3,4 micromol/L y 20,9 +/- micromol/L respectivamente.
Subject(s)
Humans , Female , Infant, Newborn , Blood , Carnitine , Umbilical Cord , ColombiaABSTRACT
Free and total carnitine quantification is important as a complementary test for the diagnosis of unusual metabolic diseases, including fatty acid degradation disorders. The present study reports a new method for the quantification of free and total carnitine in dried plasma specimens by isotope dilution electrospray tandem mass spectrometry with sample derivatization. Carnitine is determined by looking for the precursor of ions of m/z = 103 of N-butylester derivative, and the method is validated by comparison with radioenzymatic assay. We obtained an inter- and intra-day assay coefficient of variation of 4.3 and 2.3, respectively. Free and total carnitine was analyzed in 309 dried plasma spot samples from children ranging in age from newborn to 14 years using the new method, which was found to be suitable for calculating reference age-related values for free and total carnitine (less than one month: 19.3 ± 2.4 and 23.5 ± 2.9; one to twelve months: 28.8 ± 10.2 and 35.9 ± 11.4; one to seven years: 30.7 ± 10.3 and 38.1 ± 11.9; seven to 14 years: 33.7 ± 11.6, and 43.1 ± 13.8 æM, respectively). No difference was found between males and females. A significant difference was observed between neonates and the other age groups. We compare our data with reference values in the literature, most of them obtained by radioenzymatic assay. However, this method is laborious and time consuming. The electrospray tandem mass spectrometry method presented here is a reliable, rapid and automated procedure for carnitine quantitation