The profiling of plasma free amino acids and the relationship between serum albumin and plasma-branched chain amino acids in chronic liver disease: a single-center retrospective study

Background: It is poorly understood how an imbalance of plasma-free amino acids (PFAAs) occurs and how the imbalance shows an association with the serum albumin (sAlb) level during the progression of chronic liver disease (CLDs). The aim of this study is to elucidate the profiles of PFAAs and the relationship between sAlb and PFAAs in recent patients with CLDs during the progression. Methods: We retrospectively evaluated the 1569 data of PFAAs data obtained from 908 patients with various CLDs (CHC, CHB. alcoholic, NAFLD/NASH, PBC, AIH, PSC, and cryptogenic). In total, 1140 data of PFAAs could be analyzed in patients with CLDs dependent of their Child–Pugh (CP) score. Results: Various imbalances in PFAAs were observed in each CLDs during the progression. Univariate and multivariate analysis revealed that among 24 PFAAs, the level of plasma-branched chain amino acids (pBCAAs) was significantly associated with the CP score, especially the sAlb score, in patients with chronic hepatitis C virus (CHC), NAFLD/NASH and PBC. The correlation coefficient values between sAlb and pBCAAs-to-Tyrosine ratio (BTR) in these patients were 0.53, 0.53 and 0.79, respectively. Interestingly, although the pBCAAs in NAFLD/NASH patients varied even when the sAlb was within the normal range, the pBCAAs tended to be low when the sAlb was below the normal range. Conclusions: Although a decrease in the level of pBCAAs was observed during the progression regardless of the CLD etiology, the level of total pBCAAs was independently associated with the sAlb level in the PFAAs of CHC, PBC and NAFLD/NASH. The correlation between sAlb and BTR showed the highest value in PBC patients among the patients with CLDs. A decrease in pBCAAs often occurred in NASH even when the sAlb level was kept in the normal range.