Table 4.

Percentage difference in geometric mean metabolite LC-MS peak areas, by season of blood drawa

May–Jul vs. Feb–AprAug–Oct vs. Feb–AprNov–Jan vs. Feb–Apr
Metabolite categoryNFeb–AprPercentage difference, median (10th–90th percentiles)Percentage of metabolites within 15% of referentPercentage difference, median (10th–90th percentiles)Percentage of metabolites within 15% of referentPercentage difference, median (10th–90th percentiles)Percentage of metabolites within 15% of referent
Amines5Referent−1.2 (−13.4 to 9.5)100%3.7 (−13.9 to 12.1)100%−2.0 (−15.8 to 3.0)80%
Amino acid derivatives13Referent2.5 (−2.4 to 6.0)100%6.2 (1.6 to 14.0)100%−4.4 (−9.9 to 3.1)100%
Amino acids28Referent1.7 (−2.7 to 19.0)86%5.3 (−0.8 to 23.9)82%−3.2 (−6.4 to 2.6)100%
Bile acids5Referent13.7 (0.2 to 27.2)80%45.7 (21.2 to 53.7)0%2.5 (−6.6 to 30.2)80%
Lipids and lipid metabolites88Referent−1.4 (−4.7 to 3.4)100%−2.8 (−9.9 to 3.6)98%−1.6 (−7.6 to 2.1)100%
Organic acids11Referent5.4 (−0.6 to 37.3)64%6.2 (0.1 to 35.0)55%−0.1 (−1.9 to 9.5)91%
Purines, pyrimidines, and derivatives3Referent5.9 (0.5 to 8.4)100%10.9 (0.5 to 20.4)67%3.1 (−0.4 to 8.7)100%
Vitamins3Referent15.4 (3.9 to 16.9)33%7.6 (−5.0 to 12.3)100%2.7 (−1.1 to 27.3)67%
Otherb10Referent4.3 (−26.8 to 21.3)50%4.9 (−4.4 to 19.6)90%−2.0 (−17.2 to 4.0)90%
  • NOTE: N, number of metabolites.

  • aGeometric means were adjusted for age at blood draw (years, continuous), race (white, non-white), body mass index (continuous, kg/m2), physical activity (metabolic equivalent-hr/wk, continuous), sex/menopausal status (female/premenopausal, female/postmenopausal and no hormone therapy use, female/postmenopausal and hormone therapy use, male), and total caloric intake (kcal, continuous).

  • bOther metabolites include allantoin, cotinine, creatine, creatinine, hippurate, hydroxyphenylacetate, phenylethylamine, salicylurate, sorbitol, and uracil.