Observations on the Nitrogen Metabolism of Patients with Portal Cirrhosis

Abstract

In two subjects without hepatic disease, and in six patients with advanced portal cirrhosis and a history of hepatic coma, nitrogen balance and serum amino acid concentrations were measured during alternating periods of 120-g protein and 2-g protein isocaloric (35 kcal/kg body wt per day) diets. The 2-g protein diet was a chemically defined liquid formula. The cirrhotics differed from the nonhepatic subjects in these respects: a) On the 120-g protein diet, the nonhepatic cases were within ±1 g of nitrogen equilibrium. The cirrhotics showed an apparent +3 to +11 g/day nitrogen balance, due to a markedly lower excretion of urea than the nonhepatic cases. b) The cirrhotics but not the nonhepatic cases showed 2- to 15- fold elevations above normal in fasting serum concentrations of methionine, tyrosine, phenylalanine, and proline while consuming the high protein diet. These abnormalities in the fasting serum amino acid pattern were improved or corrected by 2-10 days of treatment with the 2-g, 35 kcal/kg body wt liquid diet. c) The serum total α-amino nitrogen concentration, normally 5–7 mg/100 ml, did not increase detectably in the two nonhepatic subjects 2 or 4 hr after a 60-g protein meal. In contrast, this value regularly increased from 8 to 11 mg/100 ml in the cirrhotic subjects at 2 or 4 hr.