Quantitative testing of liver function compared to prognostic scores in patients with primary biliary cirrhosis

Evaluation of quantitative liver function tests in HIV-positive patients under anti-retroviral therapy

Background and aims

Quantitative tests of liver function (QTLF) which are based on the hepatic metabolism or clearance of test substances have been successfully used to predict prognosis of a variety of different liver diseases. Still sufficient data in HIV-patients under anti-retroviral therapy (ART) are lacking. Therefore, the aim of this prospective study was to investigate if and to what extent ART influences a broad panel of quantitative tests of liver function in patients with HIV-infection.

Patients and methods

Nineteen patients (14 males, 5 females, mean age 40 years) with HIV-infection underwent QTLF including lidocaine half-life test (LHT), galactose elimination capacity (GEC), and indocyanine green clearance (IGC). These tests were performed before and 3 to 6 months after initiation of anti-retroviral therapy. Twenty age-matched healthy, medication-and virus-free adults served as controls.

Results

Lidocaine half-life was significantly lower in HIV-patients without ART. Combining anti-retroviral therapies shifted cytochrome p450 activity back into standard ranges. Galactose elimination capacity as a parameter of cytosolic liver function and indocyanine green clearance as a parameter of liver perfusion were not affected by ART.

Conclusions

QTLF may be a tool to predict prognosis or hepatic complications in HIV-infected patients with liver disease. Early determination of lidocaine half-life seems to be useful - this should be considered during the treatment of HIV-positive individuals.

Cholestatic syndromes

Further insights into the cellular and molecular mechanisms underlying hepatobiliary transport function and its regulation now permit a better understanding of the pathogenesis and treatment options of cholestatic liver diseases. Identification of the molecular basis of hereditary cholestatic syndromes will result in an improved diagnosis and management of these conditions. New insights into the pathogenesis of extrahepatic manifestations of cholestasis (eg, pruritus) have facilitated new treatment strategies. Important new studies have been published about the pathogenesis, clinical features, diagnosis, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, drug-induced cholestasis, and viral cholestatic syndromes.

Inducibility of microsomal liver function may differentiate cirrhotic patients with maintained compared with severely compromised liver reserve

BACKGROUND AND AIM

Quantitative tests of liver function (QTLF) can be modulated by enzyme-inducing agents. The objective of the study was to examine changes in QTLF after treatment with Phenobarbital, a potent cytochrome P450-inducing agent.

METHODS

Forty-six consecutive patients with liver cirrhosis Child-Pugh score B and C (34 alcoholic, 12 hepatitis C) and a compromised aminopyrine breath test (ABT) were included. Thirty-six patients (group I) received phenobarbitone (150 mg) for 7 days. Ten patients (group II) received a placebo. The QTLF, which included ABT (microsomal liver function), galactose elimination capacity (GEC, cytosolic liver function), sorbitol clearance (SCl, liver plasma flow) and indocyanine green clearance (ICG, liver perfusion) was carried out before and after pharmacological induction.

RESULTS

Group I showed a basal ABT of 0.18 +/- 0.11% dose.kg/mmol CO2 (normal >0.6%), which increased significantly after induction (172%, P < 0.05), whereas in group II the ABT values did not change. In group IB, a subgroup of group I which exceeded the basal threshold value of 0.30% after stimulation (n = 22), the ABT values increased significantly to 0.44 +/- 0.17% (244%, P < 0.01). The GEC, SCl and ICG remained unchanged before and after induction.

CONCLUSIONS

After pharmacological induction, microsomal liver function increased significantly in a subgroup of patients with liver cirrhosis, whereas the GEC, SCl and ICG remained unchanged. Inducibility of the microsomal liver function could be used as a novel parameter of functional hepatic reserve and prognosis in cirrhosis.

Review article: breath testing for human liver function assessment

Carbon-labelled breath tests were proposed as tools for the evaluation of human liver function 30 years ago, but have never become part of clinical routine. One reason for this is the complex role of the liver in metabolic regulation, making it difficult to provide essential information for the management of patients with liver disease with a single test and to satisfy the hepatology community. As a result, a battery of breath tests have been developed. Depending on the test compound administered, different metabolic pathways (microsomal, cytosolic, mitochondrial) can be examined. Most available data come from microsomal function tests, whilst information about cytosolic and mitochondrial liver function is more limited. However, breath tests have shown promise in some studies, in particular to predict the outcome of patients with chronic liver disease or to monitor hepatic function after treatment. Whilst we await new substrates that can be used to measure liver function in a more valid manner, and large prospective studies to assess the usefulness of available test compounds, the aim of this review is to describe how far we have come in this controversial and unresolved issue.