Low availability of carnitine precursors as a possible reason for the diminished plasma carnitine concentrations in pregnant women

<p>Abstract</p> <p>Background</p> <p>It has been shown that plasma carnitine concentrations decrease markedly during gestation. A recent study performed with a low number of subjects suggested that this effect could be due to a low iron status which leads to an impairment of carnitine synthesis. The present study aimed to confirm this finding in a greater number of subjects. It was moreover intended to find out whether low carnitine concentrations during pregnancy could be due to a reduced availability of precursors of carnitine synthesis, namely trimethyllysine (TML) and γ-butyrobetaine (BB).</p> <p>Methods</p> <p>Blood samples of 79 healthy pregnant women collected at delivery were used for this study.</p> <p>Results</p> <p>There was only a weak, non-significant (P > 0.05), correlation between plasma concentration of ferritin and those of free and total carnitine. There was no correlation between other parameters of iron status (plasma iron concentration, hemoglobin, MCV, MCH) and plasma concentration of free and total carnitine. There were, however, significant (P < 0.05) positive correlations between concentrations of TML and BB and those of free and total carnitine in plasma.</p> <p>Conclusions</p> <p>The results of this study suggest that an insufficient iron status is not the reason for low plasma carnitine concentrations observed in pregnant women. It is rather indicated that low plasma carnitine concentrations are caused by a low availability of precursors for carnitine synthesis during gestation.</p

Abnormal Newborn Screening in a Healthy Infant of a Mother with Undiagnosed Medium-Chain Acyl-CoA Dehydrogenase Deficiency

A neonate with low blood free carnitine level on newborn tandem mass spectrometry screening was evaluated for possible carnitine transporter defect (CTD). The plasma concentration of free carnitine was marginally reduced, and the concentrations of acylcarnitines (including C6, C8, and C10:1) were normal on confirmatory tests. Organic acids in urine were normal. In addition, none of the frequent Faroese SLC22A5 mutations (p.N32S, c.825-52G>A) which are common in the Danish population were identified. Evaluation of the mother showed low-normal free carnitine, but highly elevated medium-chain acylcarnitines (C6, C8, and C10:1) consistent with medium-chain acyl-CoA dehydrogenase deficiency (MCADD). The diagnosis was confirmed by the finding of homozygous presence of the c.985A>G mutation in ACADM