Measurement of hepatic functional mass by means of 13C-methacetin and 13C-phenylalanine breath tests in chronic liver disease: comparison with Child-Pugh score and serum bile acid levels

Abstract

Aim: To evaluate and compare the clinical usefulness of 13C-phenylalanine and 13C-methacetin breath tests in quantitating functional hepatic mass in patients with chronic liver disease and to further compare these results with those of conventional tests, Child-Pugh score and serum bile acid levels.

Methods: One hundred and forty patients (50 HCV-related chronic hepatitis, 90 liver cirrhosis patients) and 40 matched healthy controls were studied. Both breath test and routine liver test, serum levels of cholic and chenodeoxycholic acid conjugates were evaluated.

Results: Methacetin breath test, expressed as 60 min cumulative percent of oxidation, discriminated the hepatic functional capacity not only between controls and liver disease patients, but also between different categories of chronic liver disease patients. Methacetin breath test was correlated with liver function tests and serum bile acids. Furthermore, methacetin breath test, as well as serum bile acids, were highly predictive of Child-Pugh scores. The diagnostic power of phenylalanine breath test was always less than that of methacetin breath test.

Conclusion: Methacetin breath test represents a safe and accurate diagnostic tool in the evaluation of hepatic functional mass in chronic liver disease patients.

Figures

Figure 1

Methacetin and phenylalanine breath tests: cumulative percent of oxidation at 60 and 120 min. A: Methacetin breath test: cumulative percent of oxidation at 60 and 120 min. CTR = controls; CH = chronic hepatitis; LCA = liver cirrhosis Child A; LCB = liver cirrhosis Child B; LCC = liver cirrhosis Child C. CTR vs CH, LCA, LCB, LCC: P<0.001 CH vs LCA, LCB, LCC: P<0.001 LCA vs LCB, LCC: P<0.001 LCB vs LCC: P<0.001. B: Phenylalanine breath test: cumulative percent oxidation at 60 and 120 min. CTR = controls; CH = chronic hepatitis; LCA = liver cirrhosis Child A; LCB = liver cirrhosis Child B; LCC = liver cirrhosis Child C. CTR vs LCB, LCC: P<0.001 CH vs LCB, LCC: P<0.001 LCA vs LCC: P<0.05.

Figure 2

Serum levels of cholic acid (CCA) and chenodeoxycholic acid (CDCA) conjugates. CTR = controls; CH = chronic hepatitis; LCA = liver cirrhosis Child A; LCB = liver cirrhosis Child B; LCC = liver cirrhosis Child C. aP<0.05 vs CH, LCA, LCB, LCC bP<0.001 vs LCA, LCB, LCC dP<0.001 vs LCB, LCC.

Figure 3

Area under the receiver operating characteristic (ROC) curves compared to the methacetin and phenylalanine breath tests between control subjects and liver disease patients as well as between chronic hepatitis and Child-Pugh A cirrhosis patients. A: Area under the receiver operating characteristic (ROC) curves compared to methacetin and phenylalanine breath tests between control subjects and liver disease patients. --M60 = cumulative percent oxidation of methacetin at 60 mins; -P60 = cumulative percent oxidation of phenylalanine at 60 min; B: Area under the receiver operating characteristic (ROC) curves compared to methacetin and phenylalanine breath tests between chronic hepatitis and Child-Pugh A liver cirrhosis patients. -M60 = cumulative percent oxidation of methacetin at 60 mins; --P60 = cumulative percent of oxidation of phenylalanine at 60 mins.