Binding of tryptophan to albumin in liver cirrhosis: a reappraisal of the problem.
The competition of free fatty acids and bilirubin in the binding of tryptophan to albumin was studied in 12 controls and 36 cirrhotics at various stages of hepatic encephalopathy. Total tryptophan was not significantly altered in cirrhotics, while free tryptophan progressively increased with the deterioration of their mental state. Bound tryptophan levels were consequently reduced in patients with cirrhosis, mainly in the presence of hepatic encephalopathy, and strictly correlated with albumin (r = 0.80). The ratio bound tryptophan/albumin, which represents the muMoles of tryptophan bound by 1 gram of albumin, did not show significant difference in the various groups of patients. No correlation was found between this ratio and the levels of free fatty acids and bilirubin, which were raised in cirrhotics. Our data suggest that the fall in albumin levels, but not the increase in free fatty acids or bilirubin, may play a role in increasing free tryptophan levels in cirrhotics. Thus, marked hypoalbuminemia may be a risk factor of hepatic encephalopathy in patients with cirrhosis.
D000418:Albumins; D001663:Bilirubin / Q000378:metabolism; D001667:Binding, Competitive; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006501:Hepatic Encephalopathy / Q000378:metabolism; D006801:Humans; D008103:Liver Cirrhosis / Q000378:metabolism*; D011485:Protein Binding; D014364:Tryptophan / Q000378:metabolism*
D000418:Albumins; D005230:Fatty Acids, Nonesterified; D014364:Tryptophan; D001663:Bilirubin