Relative carnitine deficiency

Premature infants are born with a relative inability to synthesize carnitine, although at birth the plasma concentration of carnitine is higher in pre-term neonates than in term infants (Novak et aL, 1981). It has been suggested that the long chain fatty acids found in intravenous lipid emulsions may not be adequately metabolized because of a relative carnitine deficiency (Penn et al., 1980). Carnitine facilitates the transfer of free fatty acids across the mitochondrial membrane. In its absence, P-oxidation of long chain fatty acids is curtailed, and cellular energy metabolism is... 

Fig. 3.2.8a-c Profiles of acylcarnitines as their methyl esters in cell culture medium (precursor of m/z 99 scan) following the in vitro probe assay in fibroblast cultures of a normal control (a) and a patient with the milder (b) and the more severe variant (c) of VLCAD deficiency. Note the more prominent elevation of dodecanoyl- (Ci2 m/z 358 peak 1) and myristoylcarnitine (Ci4 m/z 386 peak 2) compared to a relatively normal accumulation of palmitoylcarnitine ( , m/z 416 peak 3) in the milder VLCAD variant compared to the severe variant, where palmitoylcarnitine is markedly elevated. The asterisks represent the internal standards (from left to right) d3-acetyl-carnitine (C2 m/z 221), d9-isovalerylcarnitine (C5 m/z 269), d3-octanoylcarnitine (C8 m/z 305), d3-dodecanoylcarnitine (Ci2 m/z 361), and d3-palmitoylcarnitine ( m/z 419)... 

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