Hypotyrosinemia, hypocystinemia, and failure to retain nitrogen during total parenteral nutrition of cirrhotic patients.

Six patients with gastrointestinal malabsorption and 12 with alcoholic cirrhosis received total parenteral nutrition for 4 wk. Freamine II, the source of the amino acids, is nearly devoid of cystine and tyrosine. We monitored daily nitrogen balance and other nutritional parameters and 22 plasma amino acids. Malabsorbers had a strongly positive nitrogen balance and improvements in nutritional parameters. Plasma amino acids were maintained within or above their normal fasting ranges. Eight of 12 cirrhotics resembled malabsorbing patients in terms of positive nitrogen balance, improved nutritional parameters, and plasma amino acids. In 4 cirrhotics, nitrogen balance remained negative and nutritional repletion failed to occur. Plasma cystine and tyrosine fell to below 30% of their normal fasting means. In 2 of these patients, oral supplements of cystine and tyrosine were given during the fifth week of parenteral nutrition. Plasma cystine and tyrosine were normalized, nitrogen balance became positive, and other repletion indicators demonstrated recovery. We conclude that in 4 cirrhotics, repletion was blocked by deficiencies of cystine and tyrosine, resulting from hepatic inability to synthesize cystine from methionine and tyrosine from phenylalanine.