Reproducibility, Temporal Variability, and Concordance of Serum and Fecal Bile Acids and Short Chain Fatty Acids in a Population-Based Study

Abstract

Background: Bile acid (BA) and short chain fatty acid (SCFA) production is affected by diet and microbial metabolism. These metabolites may play important roles in human carcinogenesis. Methods: We used a fully quantitative targeted LC-MS/MS system to measure serum and fecal BA and SCFA concentrations in 136 Costa Rican adults at study baseline and 6-months. We randomly selected 50 participants and measured their baseline samples in duplicate. Our objective was to evaluate: Technical reproducibility; 6-month temporal variability; and concordance between sample type collected from the same individual at approximately the same time. Results: Technical reproducibility was excellent, with intraclass correlation coefficients (ICC) ≥0.83 for all BAs except serum tauroursodeoxycholic acid (ICC = 0.72) and fecal glycolithocholic acid (ICC = 0.66) and ICCs ≥0.81 for all SCFAs except serum 2-methylbutyric acid (ICC = 0.56) and serum isobutyric acid (ICC = 0.64). Temporal variability ICCs were generally low, but several BAs (i.e., deoxycholic, glycoursodeoxycholic, lithocholic, taurocholic, and tauroursodeoxycholic acid) and SCFAs (i.e., 2-methylbutyric, butyric, propionic, and valeric acid) had 6-month ICCs ≥0.44. The highest degree of concordance was observed for secondary and tertiary BAs. Conclusions: Serum and fecal BAs and SCFAs were reproducibly measured. However, 6-month ICCs were generally low, indicating that serial biospecimen collections would increase statistical power in etiologic studies. The low concordance for most serum and fecal metabolites suggests that consideration should be paid to treating these as proxies. Impact: Our findings will inform the design and interpretation of future human studies on associations of BAs, SCFAs, and potentially other microbial metabolites, with disease risk.

A prospective investigation of serum bile acids with risk of liver cancer, fatal liver disease, and biliary tract cancer

“…While we cannot rule out potential confounding by unmeasured (e.g., primary sclerosing cholangitis) or unknown risk factors, [ 46 ] our results were not meaningfully altered by adjustment for measured risk factors (i.e., diabetes and alcohol intake) or in sensitivity analyses excluding individuals with a self‐reported history of gallstones or cirrhosis. Our study lacked serial blood collections, and serum BA concentrations may vary considerably within individuals over time [ 33 ] ; thus, longitudinal studies documenting changes in BA concentrations over time would be informative. Finally, although associations between BAs and biliary tract cancer were no longer significant after adjusting for multiple comparisons, to our knowledge, this is the first epidemiologic study of serum BAs and biliary tract cancer.…”

“…Serum samples were analyzed for the following 15 of the most abundant BAs at Metabolon Inc.: chenodeoxycholic acid (CDCA), cholic acid (CA), GCDCA, taurochenodeoxycholic acid (TCDCA), GCA, taurocholic acid (TCA), DCA, LCA, glycodeoxycholic acid (GDCA), taurodeoxycholic acid (TDCA), glycolithocholic acid (GLCA), taurolithocholic acid (TLCA), ursodeoxycholic acid (UDCA), glycoursodeoxycholic acid (GUDCA), and tauroursodeoxycholic acid (TUDCA). [ 33 ] Case and matched‐control samples were placed next to each other in the same batch but in random order. Blinded quality control (QC) samples (n = 40 study duplicates) were regularly spaced throughout each batch.…”

Behavioral factors and SARS-CoV-2 transmission heterogeneity within a household cohort in Costa Rica

“…The one-way Intraclass correlation coefficient (ICC) for nucleocapsid within-plate duplicate was 0.94 with 95% CI 0.87 -0.97; the ICC for spike within-plate duplicate was 0.95 with 95% CI 0.89 -0.98; the ICC for nucleocapsid across-plate duplicate was 0.71 with 95% CI 0.44 -0.87; the ICC for spike within-plate duplicate was 0.87 with 95% CI 0.72 -0.94. In addition 25 pre-pandemic samples from a population study in Costa Rica 22 were tested as negative controls to ensure assay validity; all were classified as seronegative, as expected.…”

The human microbial exposome: expanding the Exposome-Explorer database with gut microbial metabolites

“…However, faecal samples are not easily collected in epidemiological studies and most often not available in large cohort studies. Measurements of bile acids and short chain fatty acids were compared in serum and faeces and poor correlations were observed between measurements in the two matrices [29]. The most likely explanation of this absence of correlations is the large heterogeneity of faecal samples [30] coupled to the small amount of sample collected (200 mg) and analysed in the study.…”

“…The most likely explanation of this absence of correlations is the large heterogeneity of faecal samples [30] coupled to the small amount of sample collected (200 mg) and analysed in the study. This heterogeneity also explains the large temporal variability when measuring bile acids and short chain fatty acids in stool repeat samples collected six months apart [29]. A much higher reproducibility was systematically observed when the same microbial metabolites were measured in serum repeat samples [29], most likely explained by homogenization of microbial metabolites in several litres of blood.…”