Development and application of a fluorescent immunochromatographic assay for metabolite G-DCA quantification in ICP

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder characterized by dysregulated bile acid metabolism, which can lead to severe adverse pregnancy outcomes. Glycine-conjugated deoxycholic acid (G-DCA) is a small-molecule metabolite that has been reported to be elevated in the serum of patients with ICP; however, its clinical application remains limited because conventional chromatographic methods for its quantification are time-consuming, costly, and not well-suited for rapid clinical screening. To address this gap, we developed a time-resolved fluorescence immunochromatographic test strip (TRF-ICTS) for the quantitative detection of serum G-DCA. Based on a small-molecule competitive binding design, the assay requires only 10 μl of serum sample and enables rapid detection within 16 min. The TRF-ICTS demonstrated good analytical performance, with a linear range of 0.05-10.0 ng/ml and a detection limit of 0.074 ng/ml, and maintained stable performance over two weeks of storage at both 4°C and 37°C. The results showed good quantitative agreement with LC-MS/MS measurements. Evaluation of sensitivity, specificity, and precision demonstrated that all parameters were within acceptable ranges. Clinical validation using serum samples from ICP patients and healthy pregnant women showed that G-DCA levels were elevated across different trimesters and were more pronounced in patients with severe ICP and adverse pregnancy outcomes. Overall, the developed TRF-ICTS provides a rapid and sensitive method for quantifying G-DCA, which may serve as a complementary biomarker for ICP diagnosis and disease stratification, providing additional insights into bile acid changes following UDCA treatment.