Table 1

Results of principal components analysis

FactorMetabolites within factorDescriptionEigen valueVarianceCumulative variance
1C8 C5-DC C10:1 C10 C12:1 C12 C14:2 C14:1 C14 C16 C8:1-OH/C6:1-DC C8:1-DC C16:2 C16:1 C18:2Medium- and long-chain acylcarnitines13.10.170.17
2FA-C14:0 FA-C16:1 FA-C16:0 FA-α-C18:3 FA-C18:2 FA-C18:1 FA-C18:0 FA-C22:6 Free fatty acids Hydroxybutyrate Ketones C2Free fatty acids and by-products of fatty acid oxidation9.60.130.30
3C2 C6-DC C10-OH/C8-DC C12-OH/C10-DC C14:1-OH C18 C18:1 C18:2 C14-OH/C12-DC C18:1-OH C16:1-OH/C14:1-DC C16Long-chain acylcarnitines and C2-acylcarnitine6.40.090.39
4Proline Valine Leucine/Isoleucine Methionine Phenylalanine Tyrosine Uric acid HistidineLarge neutral amino acids and uric acid4.30.060.44
5C8:1 C10:3 GlucoseMedium-chain acylcarnitines and glucose3.50.050.49
6C3 C4/Ci4 C5sShort-chain acylcarnitines3.10.040.53
7Glutamate/Glutamine Hydroxybutyrate Ketones GlucoseGlutamate/Glutamine2.70.050.57
8Glycine SerineOne-carbon metabolism2.30.030.60
9C20 C16-OH/C14-DC C18:1-DCLong-chain and hydroxy or dicarboxy acylcarnitines2.10.030.63
10Alanine LactateAlanine and lactate2.00.030.66
11C6 C5OH/C3-DCShort-chain and hydroxy or dicarboxy acylcarnitine1.70.020.68
12Citrulline Arginine C10:2 C18-OH/C16-DCUrea cycle, medium-chain acylcarnitine, and hydroxy or dicarboxy acylcarnitine1.70.020.70
13C20:4Arachidonoyl carnitine1.50.020.72
14Ornithine FA-C20:4 (neg)Ornithine and arachidonic acid1.50.020.74
15C5:1 C18:2-OH (neg)Acylcarnitines1.60.020.76
16C22 C4-OH (neg)Acylcarnitines1.30.020.78
17Aspartate/AsparagineAspartate/Asparagine1.30.020.79
18C18-OH/C16-DC C22:6Hydroxy or dicarboxy acylcarnitine1.20.020.81
19Histidine C7-DCHistidine and dicarboxy acylcarnitine1.10.010.82
  • Key metabolites within each retained factor (i.e., metabolites with factor load ≥ |0.4|) and an overall description of each factor are presented. Italicized metabolites represent those with a factor load ≥|0.4| on a second factor. DC, dicarboxylic; FA, fatty acid.