A) Study of liver function in healthy elderly subjects using the 13C-methacetin breath test

BACKGROUND: The issue of whether or not liver function is compromised in the healthy elderly population remains unsolved. AIM: To investigate the putative age-related modifications of hepatic function using the 13C-methacetin breath test. Because endogenous CO2 production changes with age, motor activity and nutrition, a different form of processing the results was investigated. PATIENTS AND METHODS: Twenty-nine elderly subjects (mean age, 79.8 +/- 7.9 years; female/male ratio, 17/12) and 28 adult subjects (mean age, 40.6 +/- 12.3 years; female/male ratio, 13/15) underwent 13C-methacetin breath test and trans-abdominal echosonography with Doppler pulsed wave analysis of the coeliac axis and portal vein. RESULTS: Although the 13CO2 peak occurred within 15-30 min in both elderly and adult subjects, it was significantly decreased in the former (30.66% +/- 9.2% vs. 38.33% +/- 6.05%; P < 0.001), as was the cumulative excretion (33.07% +/- 7.06% vs. 39.81% +/- 5.68%; P < 0.001). When correcting for the effects of CO2 excretion by age, the age-related modification of the cumulative dose became more evident (elderly group 30.15% +/- 6.46% vs. adult group 37.97% +/- 5.92%; P < 0.0001). The elderly group also showed an increase in the intra-hepatic resistance index using Doppler pulsed wave analysis, which inversely correlated with the results of the breath test. CONCLUSIONS: Hepatic function is not well preserved in healthy humans throughout life and may be due to an increase in vascular resistance.