Are patients with primary biliary cirrhosis hypermetabolic? a comparison between patients before and after liver transplantation and controls



Wasting is common in end-stage primary biliary cirrhosis and causes concern in patients facing liver transplantation. We have quantified resting metabolic rate and diet-induced thermogenesis in seven patients with primary biliary cirrhosis, in seven patients after liver transplantation who had previously been diagnosed as having primary biliary cirrhosis and in seven controls.

Resting metabolic rate was elevated in the primary biliary cirrhosis group (4.44 ± 0.81 kJ/hr/kg body wt; mean ± S.D.) compared with the post-liver-transplantation group (3.39 ± 0.40 kJ/hr/kg body wt) (p < 0.005) and compared with control subjects (3.65 ± 0.23 kJ/hr/kg body wt) (p < 0.01). A highly significant relationship was found between the severity of liver disease in the primary biliary cirrhosis group, as assessed by Child-Pugh score, and the resting metabolic rate group (r = 0.93; p < 0.005).

After a liquid meal (41 kJ/kg body wt), the metabolic rate increased, with similar peak changes from baseline occurring in all three groups. However, the rise persisted significantly longer in the primary biliar cirrhosis patients, and thus the integrated mean postprandial energy expenditure over the 4-hr postprandial observation period was greater in the primary biliary cirrhosis group than in the other two groups (p < 0.001).

Fasting glucose and protein oxidation rates were similar between groups, but fasting fat oxidation rate was higher in the primary biliary cirrhosis group (3.90 ± 0.83 kJ/hr/kg body wt) than in the post-liver-transplantation group (2.11 ± 0.90 kJ/hr/kg body wt) (p < 0.025) and than in the control group (2.49 ± 1.19 kJ/hr/kg body wt) (p < 0.05). Postprandial glucose oxidation rates were similar in all groups, but the protein oxidation rate was lower in the primary biliary cirrhosis group than in the other two groups (p < 0.01). The fat oxidation rate remained higher after food intake in the primary biliary cirrhosis group than in the post-liver-transplantation group (p < 0.05), but no significant differences were found between the primary biliary cirrhosis and control groups or between the post-liver-transplantation and control groups. No differences in total fasting plasma free fatty acids were seen between groups, but the level of stearic acid was higher in the control group (41.3 ± 10.3 μmol/L) than in the primary biliary cirrhosis group (27.5 ± 9.2 μmol/L) (p < 0.05) or than the post-liver-transplantation group (26.9 ± 6.6 μmol/L) (p < 0.05).

These data suggest that, as liver disease progresses, resting. metabolic rate increases. This, together with the greater overall diet-induced thermogenesis in these patients, could make a significant contribution to increased energy expenditure and thereby exacerbate malnutrition.