13C-methacetin breath test as liver function test in patients with chronic hepatitis C virus infection

13C-methacetin breath test shortened: 2-point-measurements after 15 minutes reliably indicate the presence of liver cirrhosis

BACKGROUND AND GOALS

The 13C-methacetin breath test (MBT) measures the activity of the cytochrome P450 dependent enzyme system and has been developed to assess the functional hepatic mass. We evaluated simple modifications of the 13C-MBT to further increase its practicability and therefore clinical acceptance.

STUDY

One hundred and four patients with different chronic liver diseases (including 35 patients with histologically proven cirrhosis) and 65 healthy controls underwent the 13C-MBT. Breath test results of 2-point measurements were compared with conventional breath test results (cumulative recovery after 30 min) and liver histology.

RESULTS

The 2-point-measurement at 0 and 15 minutes (with a cut-off <14.6 per thousand delta over baseline) had 92.6% sensitivity and 94.1% specificity in identifying the presence of cirrhosis compared with liver histology. The 2-point-measurements at 5 and 10 minutes also provided good discrimination between cirrhotic and noncirrhotic patients.

CONCLUSIONS

The 13C-MBT using 2-point-measurement of breath samples at baseline and after 15 minutes reliably indicates decreased liver function in liver cirrhosis. This simplification of the 13C-MBT will increase practicability and cost efficiency, thus facilitating its clinical acceptability.

13C-methacetin and 13C-galactose breath tests can assess restricted liver function even in early stages of primary biliary cirrhosis

OBJECTIVE

The 13C-methacetin breath test quantitatively evaluates cytochrome P450-dependent liver function. The 13C-galactose breath test non-invasively measures the galactose oxidation capacity of the liver. The aim of this study was to find out whether these breath tests are sensitive parameters also in non-cirrhotic patients with primary biliary cirrhosis.

MATERIAL AND METHODS

Nineteen patients with early-stage primary biliary cirrhosis (no cirrhotic alterations in the liver biopsy, Ludwig stage I-III) and 20 healthy controls underwent the 13C-methacetin and 13C-galactose breath tests.

RESULTS

Patients with primary biliary cirrhosis metabolized less 13C-methacetin than controls (cumulative recovery within 30 min 7.5+/-2.4% versus 14.0+/-2.6%; p < 0.001). When a cut-off > 9.8% was used for the cumulative recovery after 30 min, the methacetin breath test reached 84.2% sensitivity and 95.0 specificity. In the 13C-galactose breath test, the percentage recovery at 60 min in patients was 3.1+/-1.3%/h, and 6.3+/-1.1%/h in controls (p < 0.001). Using a cut-off > 4.7%/h, the galactose breath test reached 89.5% sensitivity and 95.0 specificity.

CONCLUSIONS

In non-cirrhotic, early-stage, primary biliary cirrhosis the 13C-methacetin breath test and the 13C-galactose breath test reliably indicate decreased liver function. The 13C-galactose breath test can also predict the histological score.

Do we still need a liver biopsy? Are the serum fibrosis tests ready for prime time?

Liver biopsy has been in use for more than a century for diagnosis and staging of acute and chronic liver diseases. Several serum markers and panels offer the opportunity to assess the extent of liver disease noninvasively and spare some patients the risks associated with percutaneous liver biopsy, but only a few of the noninvasive serum markers allow the determination of different stages of fibrosis on a continuum similar to that achieved with liver biopsy. This article reviews the results of recent published and preliminary studies on serum markers, focusing on their comparison with liver biopsy and their clinical utility.

PATIENT AGE IS A STRONG INDEPENDENT PREDICTOR OF 13C-AMINOPYRINE BREATH TEST RESULTS: A COMPARATIVE STUDY WITH HISTOLOGY, DUPLEX-DOPPLER AND A LABORATORY INDEX IN PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION

1. Noninvasive tests for the staging of chronic hepatitis C virus (HCV) infection would be an attractive alternative to liver biopsy. The 13C-aminopyrine breath test (ABT) has been proposed for the noninvasive assessment of hepatic function and partly correlates with fibrosis. We aimed to investigate causes for the lack of discriminatory power for different degrees of hepatic fibrosis. 2. Eighty-three patients (median age 49 years (28-78 years)) with chronic HCV infection underwent the ABT after an oral load of 75 mg N,N-dimethyl-13C-aminopyrine. Portal vein flow was assessed by duplex-Doppler and a laboratory index (aspartate aminotransferase to platelet ratio index or APRI) was calculated. Parameters were compared with liver histology. 3. The cumulative 13C-recovery differed significantly between patients without relevant fibrosis (fibrosis score 0-2) and cirrhosis (5-6), beginning after 30 min of sampling (P < 0.05). The ABT did not discriminate patients with fibrosis scores 3-4 from the remaining two patient groups. Sensitivity and specificity for the prediction of cirrhosis was 73.4-82.8% and 63.2-68.4%, depending on the sampling time. Compared with the fibrosis score (P = 0.04), patient age was a highly significant independent predictor for the 13C-recovery (P < 0.0001). Aspartate aminotransferase to platelet ratio index and duplex-Doppler predicted cirrhosis with 76.6%vs. 87.5% sensitivity and 63.2%vs. 68.4% specificity. 4. Our data suggest an age-dependent decrease of cytochrome P450 activity which probably accounts for the large overlap of ABT results that preclude clear differentiation. This is also consistent with former pharmacodynamic trials. Age-adapted reference ranges could improve ABT results.

Thrombocytopenia as a surrogate for cirrhosis and a marker for the identification of patients at high-risk for hepatocellular carcinoma

BACKGROUND

The objective of this study was to examine the usefulness of platelet counts in the diagnosis of cirrhosis and for identifying high-risk individuals in a community-based hepatocellular carcinoma (HCC) screening program.

METHODS

Pilot Study 1 determined the correlation between platelet counts and pathologic hepatic fibrosis scores among individuals with chronic hepatitis B virus (HBV) infection (n = 122 patients) and hepatitis C virus (HCV) infection (n = 244 patients). Pilot Study 2 investigated proportions of individuals with thrombocytopenia (<150 x 10(3)/mm(3)) among patients with HCC (n = 4042 patients). Pilot Study 3 demonstrated the correlation between platelet counts and ultrasonographic (US) parenchyma scores among anti-HCV-positive individuals (n = 75 patients). The core study was a 2-stage, community-based screening for HCC among residents age 40 years or older in townships with a high prevalence of anti-HCV (n = 4616 individuals) and in townships with a low prevalence of anti-HCV (n = 1694 individuals). Patients with thrombocytopenia were identified for US and alpha-fetoprotein screening.

RESULTS

Among the individuals who were positive for anti-HCV, platelet counts decreased according to increased pathologic fibrosis scores or US scores for liver parenchyma disease: The best cutoff platelet count was 150 x 10(3)/mm(3) for a diagnosis of cirrhosis. The sensitivity and specificity were 68.2% and 76.4%, respectively, for pathologic cirrhosis and 76.2% and 87.8%, respectively, for US cirrhosis. Forty-eight percent of patients with HCC were thrombocytopenic. The proportion of thrombocytopenia was significantly greater in patients with HCV-related HCC (63%) than in patients with HBV-related HCC (42%). In the townships with high and low anti-HCV prevalence, the prevalence of thrombocytopenia was 17.9% and 6.1%, respectively, (P < .001), respectively. Twenty-five patients were diagnosed with HCC, and all of those patients resided in the high-prevalence township.

CONCLUSIONS

Thrombocytopenia was a valid surrogate of cirrhosis and a valid marker for the identification of individuals at high-risk for HCC, especially in areas that had a high prevalence of HCV.