Integrated untargeted and targeted metabolomics identifies and validates urinary bile acid biomarkers for the diagnosis of intrahepatic cholestasis of pregnancy.

BACKGROUND

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-specific liver disorder and is characterized by unexplained pruritus and elevated serum bile acid levels, typically in the third trimester. Excessive bile acid accumulation is associated with maternal discomfort and adverse fetal outcomes, underscoring the need for timely and accurate diagnosis.

METHODS

We enrolled 76 pregnant women. In the discovery cohort, untargeted metabolomics was performed on paired serum and urine samples from 8 patients with ICP and 8 healthy controls to identify co-differentially expressed metabolites (co-DEMs). In the validation cohort, targeted metabolomics was used to quantify urinary bile acid co-DEMs in 30 patients with ICP and 30 controls.

RESULTS

Untargeted metabolomics identified 76 and 64 differentially expressed metabolites (DEMs) in serum and urine, respectively. Seven co-DEMs were detected in both sample types, five of which were bile acid species. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis highlighted primary bile acid biosynthesis as a key pathway associated with ICP. Targeted metabolomics showed marked increases in urinary glycocholic acid (GCA) and taurocholic acid (TCA), both of which remained significant after false discovery rate (FDR) correction, whereas cholic acid (CA) showed a more modest difference in the candidate-focused analysis. Urinary concentrations of these metabolites were positively correlated with serum total bile acid levels. Receiver operating characteristic (ROC) curve analysis showed strong diagnostic performance for GCA (AUC = 0.95) and TCA (AUC = 0.86), whereas CA showed modest performance (AUC = 0.65).

CONCLUSION

Primary bile acid biosynthesis is closely associated with ICP. Urinary GCA and TCA may serve as promising non-invasive biomarkers for the diagnosis of ICP. These findings require confirmation in larger, independent multicenter cohorts before clinical implementation.