~(13)C-phenylalanine breath test in the diagnosis of minimal hepatic encephalopathy

Objective To evaluate the effect of ~(13)C-phenylalanine breath test in diagnosis of mini- real hepatic encephalopathy(MHE).Methods Eighty patients with liver cirrhosis,20 with chronic hep- atitis B and 20 healthy controls were enrolled.The serum markers,Child-Pugh classification and scores of MHE in the three groups were evaluated.After orally administration of L-[-1-~(13)C] phenylalanine at a dose of 100 rag,the values of ~(13)CO_2 exhalation rate(~(13)C-% dose/h)and cumulative excretion(Cum)were measured at 8 different time points(0,10,20,30,45,60,90,120 min).Results Except one patient in cirrhosis group withdrew because of failure in breath test,there were 23 patients classified as Child- Pugh class A,44 as class B and 12 as class C.There were 28 patients with MHE and 51 patinets with- out.The ~(13)C-%dose/h at 20 and 30 min after administration of L-[~(13)C] phenylalanine were significant difference in cirrhosis group and healthy controls.In healthy controls and patients of class A,B or C, ~(13)C-%dose/h at 20 min were 15.8±2.0,9.2±1.9,6.2±1.2 or 3.8±0.7,respectively,and at 30 min were 14.2±2.1,7.0±1.2,5.1±0.8 or 4.4±0.5,respectively,while Cum at 60 min were 11.1±0.9, 6.73±0.8,5.0±0.6 and 3.7±0.4,and at 120 min were13.0±1.2,8.2±1.0,6.2±0.9 or 4.8±0.6, respectively(P0.01).Similar results were observed in patients with or without MHE.The ~(13)C-% dose/h at 20 min in patients with or without MHE were 7.4±2.3 vs 5.6±1.5,and at 30 min were 5.8±1.4 vs 5.0±1.0;the Cum at 60 min were 5.6±1.2 vs 4.8±0.9,and at 120 min were 6.8±1.6 vs 6.0±1.1(P0.05).Conclusions The ~(13)C-phenylalanine breath test can be used as a non-invasive assay in evaluating liver function in patients with liver cirrhosis and MHE.The ~(13)C-%dose/h at 20 and 30 min and Cum at 60 min may be the key time-point in diagnosing MHE.