The plasma amino acid profile and its relationships to standard quantities of liver function in infants and children with extrahepatic biliary atresia and preterminal liver cirrhosis.

The absolute and relative concentrations of 16 plasma amino acids in 48 mostly dystrophic infants and children (median of age 1 1/2 years) with extrahepatic biliary atresia and mainly stable preterminal cirrhosis were compared with those of controls. Patient plasma amino acid data were analysed statistically for diagnostic usefulness and correlated with standard biochemical quantities of liver function and of liver perfusion. In the patients the total amounts of non-essential and essential amino acids were reduced by 19% and with the same significance (p < 0.0005). Plasma tyrosine was increased (+40%), while taurine (-44%) and branched chain amino acids (+28.8% to -34.7%) were decreased. Methionine values varied widely. In the molar fractional plasma amino acid profile, only alanine, valine, and leucine were decreased, while threonine, methionine, tyrosine, phenylalanine, ornithine, and serine were increased. Discriminate function analysis showed that the plasma amino acid data discriminated 93.8% of the patients from controls. The concentrations of some amino acids in plasma seemed to have been influenced by protein-calorie deficiency in the patients. The valine/tyrosine ratio and the Fischer index (ratio branched chain/aromatic amino acids) were significantly reduced in the patients versus controls (1.54 +/- 0.55 vs 3.08 +/- 0.55 and 1.66 +/- 0.39 vs 3.00 +/- 0.48). A number of significant correlations (range of r: 0.37-0.59, p < 0.05, 30-48 data pairs) were calculated between plasma amino acid data and several standard biochemical quantities of liver function. The statistical analyses also showed that the Fischer index began to decrease gradually and linearly early in the progression of liver failure.(ABSTRACT TRUNCATED AT 250 WORDS)