62 Automated Total Bile Acids Assay for the Rapid Diagnosis of Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a liver disorder that occurs during pregnancy, characterized by impaired bile flow, leading to a buildup of bile acids in the liver and bloodstream. It typically manifests in the third trimester and is associated with symptoms like intense itching, particularly on the palms and soles. ICP can increase the risk of complications for both the mother and baby, including preterm labor, fetal distress, and stillbirth, making early diagnosis and management crucial. Current diagnostic tools are limited to measuring the three most common bile acids: cholic acid (CA), chenodeoxycholic acid (CDCA), and deoxycholic acid (DCA) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, the turn-around-time for most hospitals who do not perform such esoteric testing in-house can be 3-5 days, which can be too late for some patients. The objective of this study is to validate an automated enzymatic Total Bile Acids (TBA) assay to be used as a diagnostic tool for ICP in pregnant women and compare it to the gold standard LC-MS/MS method. We propose that an automated enzymatic assay will provide a sensitive and specific approach for diagnosing ICP, ultimately reducing turnaround time from days to hours. To validate this approach, our laboratory installed the Diazyme Total Bile Acids Assay on the Roche Cobas c502 platform, and validated it to clinical standards. We analyzed the validated data using EP Evaluator software to assess precision, linearity, accuracy, and for the verification of the reference interval (RI). Precision was evaluated with three different quality controls, each run twenty times, resulting in a coefficient of variation (%CV) of less than 3%. Linearity was confirmed over a range of 0.0 to 162 µmol/L. A comparison with the gold standard LC-MS/MS method revealed a bias of 6.28% in patient samples. Deming regression analysis of the correlation between the Total Bile Acids assay and LC-MS/MS showed an R value of 0.99, with a slope of 0.800 and an intercept of 3.53, indicating good agreement between the two methods. The validated reference interval for the assay was 0-10 µmol/L, based on 35 samples prospectively recruited from healthy males and females. ICP is diagnosed in patients with TBA levels above 10 µmol/L. This validated assay provides a quicker, alternative for diagnosing ICP in pregnant women, compared to sending samples to a reference lab.