Hepatocellular enzyme glutathione S-transferase alpha and intrahepatic cholestasis of pregnancy

Total serum bile acids or serum bile acid profile, or both, for the diagnosis of intrahepatic cholestasis of pregnancy

BACKGROUND

Intrahepatic cholestasis of pregnancy is a pregnancy-specific liver disorder, possibly associated with an increased risk of severe fetal adverse events. Total serum bile acids (TSBA) concentration, alone or in combination with serum aminotransferases, have been the most often used biomarkers for the diagnosis of intrahepatic cholestasis of pregnancy in clinical practice. Serum bile acid profile, composed of primary or secondary, conjugated or non-conjugated bile acids, may provide more specific disease information.

OBJECTIVES

To assess and compare, independently or in combination, the diagnostic accuracy of total serum bile acids or serum bile acids profile, or both, for the diagnosis of intrahepatic cholestasis of pregnancy in pregnant women, presenting with pruritus. To define the optimal cut-off values for components of serum bile acid profile; to investigate possible sources of heterogeneity.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic Test Accuracy Studies Register, the Cochrane Library, MEDLINE Ovid, Embase Ovid, Science Citation Index Expanded, Conference Proceedings Citation Index - Science, BIOSIS, CINAHL, two Chinese databases (CKNI, VIP), Latin American and Caribbean Health Sciences Literature (LILACS), Scientific Electronic Library Online (SciELO), Evidence Search: Health and Social Care by the National Institute for Health and Care Excellence (NICE), the World Health Organization (WHO) Reproductive Health Library (RHL), and the Turning Research into Practice database (TRIP). The most recent date of search was 6 May 2019. We identified additional references by handsearching the references of articles, meta-analyses, and evidence-based guidelines retrieved from the computerised databases, on-line trial registries, and grey literature through OpenSIGLE, National Technical Information Service (NTIS), ProQuest Dissertations & Thesis Database, and Index to Theses in Great Britain and Ireland.

SELECTION CRITERIA

Prospective or retrospective diagnostic case-control or cross-sectional studies, irrespective of publication date, format, and language, which evaluated the diagnostic accuracy of total serum bile acids (TSBA) or components of serum bile acid profile for the diagnosis of intrahepatic cholestasis of pregnancy in pregnant women of any age or ethnicity, in any clinical setting, symptomatic for pruritus.

DATA COLLECTION AND ANALYSIS

We selected studies by reading titles, abstracts, or full texts, and assessing their fulfilment of our inclusion criteria. We emailed primary authors to request missing data or individual participant data. Having extracted data from each included study, we built the two-by-two tables for each primary study and for all the index tests considered. We estimated sensitivity and specificity with their 95% confidence intervals (CI). We presented data in coupled forest plots, showing sensitivities and specificities of each study, and we plotted the studies in the Receiver Operating Characteristic (ROC) space. We performed meta-analyses adopting the hierarchical summary ROC model (HSROC) or the bivariate model to meta-analyse the data. We made indirect comparisons of the considered index tests by adding the index tests as covariates to the bivariate or HSROC models. We performed heterogeneity analysis and sensitivity analysis on studies assessing TSBA accuracy. We used Review Manager 5 (RevMan 5) and SAS statistical software, release 9.4 (SAS Institute Inc., Cary, NC, USA), to perform all statistical analyses. We used QUADAS-2 domains to assess the risk of bias of the included studies.

MAIN RESULTS

Our search yielded 5073 references, but at the end of our selection process, only 16 studies fulfilled the review inclusion criteria. Nine of these provided individual participant data. We analysed only data concerning TSBA, cholic acid (CA), glycocholic acid (GCA), chenodeoxycholic acid (CDCA), and CA/CDCA because the remaining planned index tests were assessed in few studies. Only one study had low risk of bias in all four QUADAS-2 domains. The most biased domains were the patient sampling and the reference standard domains. When considering all studies with a cut-off of 10 μmol/L, TSBA overall sensitivity ranged from 0.72 to 0.98 and specificity ranged from 0.81 to 0.97. After a sensitivity analysis excluding case-control studies, TSBA sensitivity ranged from 0.48 to 0.66 and specificity from 0.52 to 0.99. After a sensitivity analysis excluding studies in which TSBA was part of the reference standard, TSBA sensitivity ranged from 0.49 to 0.65 and specificity from 0.53 to 0.99. We found the estimates of the overall accuracy for some serum bile acid components (CA, GCA, CDCA, and CA/CDCA) to be imprecise, with the CI for sensitivity and specificity very wide or impossible to calculate. Indirect comparisons between serum bile acid profile components and TSBA were not statistically significant. None of the heterogeneity analysis performed was statistically significant, except for the timing of assessment of TSBA (onset of symptoms, peak value among multiple assessments, delivery) but without clinically relevant results. We could not analyse the diagnostic accuracy of combinations of index tests because none of the included studies carried them out, and because of the small number of included studies.

AUTHORS' CONCLUSIONS

The overall high risk of bias, the existing concern regarding applicability of the results in clinical practice, and the great heterogeneity of the results in the included studies prevents us from making recommendations and reaching definitive conclusions at the present time. Thus, we do not find any compelling evidence to recommend or refute the routine use of any of these tests in clinical practice. So far, the diagnostic accuracy of TSBA for intrahepatic cholestasis of pregnancy might have been overestimated. There were too few studies to permit a precise estimate of the accuracy of serum bile acid profile components. Further primary clinical research is mandatory. We need both further phase II and phase III diagnostic studies.

Bile acids and gestation

There are numerous profound maternal physiological changes that occur from conception onwards and adapt throughout gestation in order to support a healthy pregnancy. By the time of late gestation, when circulating pregnancy hormones are at their highest concentrations, maternal adaptations include relative hyperlipidemia, hypercholanemia and insulin resistance. Bile acids have now been established as key regulators of metabolism, and their role in gestational changes in metabolism is becoming apparent. Bile acid homeostasis is tightly regulated by the nuclear receptor FXR, which has been shown to have reduced activity during pregnancy. This review focuses on the gestational alterations in bile acid homeostasis that occur in normal pregnancy, which in some women can become pathological, leading to the development of intrahepatic cholestasis of pregnancy. As well as their important role in maternal metabolic health, we will review bile acid metabolism in the feto-placental unit.

Significance of Serum Alpha-Glutathione S-Transferase Assessment in Hepatitis C Patients with Different Alanine Aminotransferase Patterns

BACKGROUND

Alpha-Glutathione S-transferase (α-GST) is a liver enzyme which showed properties making it useful in assessment of liver cell damage. A number of studies demonstrated its early elevation in different hepatic insults, but its pattern in HCV was controversial. Consequently, we planned this work to study the significance of Serum Alpha-Glutathione S-Transferase (α-GST) assessment in hepatitis C patients with different alanine aminotransferase (ALT) patterns.

METHODS

Sixty-five untreated male patients with history of hepatitis C virus (HCV) positive antibodies and 21 healthy age- and sex-matched control subjects were enrolled in this study. Sera were collected for confirmation of the presence of HCV antibodies (by ELISA) as well as for assessment of the levels of α-GST, ALT, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl-transferase, total proteins, albumin and HCV RNA. HCV RNA was detected by the reverse transcription polymerase chain reaction (RT-PCR). Based on ALT level, patients were divided into three groups. Twelve patients with normal ALT levels (NALT), 29 with near normal ALT levels (NNALT), and 24 with high ALT levels (HALT). All data were statistically analyzed for significance and correlation as well as sensitivity, specificity, positive and negative predictive values.

RESULTS

The mean value of α-GST in HCV patients was significantly higher compared to the control with 82% sensitivity, 85% specificity, 98% positive predictive value and 63% negative predictive value. These results were more or less similar to the results of ALT and higher than the results of all the other assayed liver function tests. The sensitivity, and positive and negative predictive values of α-GST were lower than aminotransferases, but higher than the other assayed liver function tests in NNALT and HALT groups. Nevertheless, in NALT, these parameters were higher for α-GST than all the other assayed liver function tests including aminotransferases.

CONCLUSIONS

Assay of α-GST has an adjuvant in evaluation of liver cell damage in HCV patients. However, its role is much more valuable in patients with normal aminotransferases for early detection of liver cell damage.

Intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder characterized by maternal pruritus in the third trimester, raised serum bile acids and increased rates of adverse fetal outcomes. The etiology of ICP is complex and not fully understood, but it is likely to result from the cholestatic effects of reproductive hormones and their metabolites in genetically susceptible women. Equally unclear are the mechanisms by which the fetal complications occur. This article reviews the epidemiology, clinical features, diagnosis, etiology and management of ICP.