Analytical validation of a LC-MS/MS based in vitro diagnostic kit for the quantification of L-tyrosine and taurocholic acid for liver fibrosis diagnosis

FibraChek is a newly developed mass spectrometry (MS) assay kit approved by the National Medical Products Administration (NMPA) of China for quantifying L-tyrosine (Tyr) and taurocholic acid (TCA) in serum, aiding liver fibrosis diagnosis. This study aimed to assess its analytical performance. The analytical performance was investigated based on NMPA and CLSI guidelines. Method suitability in the clinical context was tested by analyzing clinical samples from liver fibrosis patients confirmed via liver biopsy. The assay enables simultaneous determination of Tyr and TCA, demonstrating compliance with performance parameters such as linearity, dynamic range, limit of detection (LOD), limit of quantification (LOQ), recovery, repeatability, reproducibility, and stability. It validated a linear range of 20-1000 μmol/L for Tyr and 10.3-618 ng/ml for TCA, maintaining stability after 5 freeze-thaw cycles for 14 months. Components remained stable for up to 7 days at room temperature and 30 days at 2-8 °C. TCA and Tyr were stable for up to 36 months at -20 °C or -80 °C. The method effectively quantified Tyr and TCA in serum from liver fibrosis patients and healthy controls. This is the first MS-based assay for non-invasive liver fibrosis detection validated for clinical use, providing a rapid and reliable analytical protocol suitable for routine analysis.