L-[1-13C]phenylalanine breath test in patients with chronic liver disease of different etiologies.

The aim of this study was to compare the oxidation of l-[1-13C]phenylalanine (13C-PheOx) in patients with chronic liver failure due to different etiologies using l-[1-13C]phenylalanine breath test. Breath samples were collected before the administration of 100 mg l-[1-13C]phenylalanine, and every 10 min thereafter until completion of 1 h. Control subjects (n=9) presented a larger cumulative percentage of 13C dose recovery (CPDR) than patients (n=124) with chronic liver disease, regardless of the etiology (7.5±0.7 vs. 4.2±0.2, p=0.001). No differences in CPDR were found considering the Child-Pugh (CP) class or etiology: alcoholic (CP A=7.7±0.7, CP B=4.1±0.5, CP C=2.0±0.3), hepatitis C virus (CP A=5.4±0.5, CP B=4.0±0.2, CP C=2.2±0.3), hepatocellular carcinoma (CP A=5.5±1.6, CP B=3.6±1.8, CP C=2.2±1.0); or cryptogenic cirrhotic patients (CP A=7.4±1.5, CP B=4.4±0.4, CP C=2.1±0.7). Results confirm that 13C-PheOx decreases in patients with cirrhosis with respect to controls, notwithstanding the etiology.