Hypertyraminemia in cirrhotic patients

Area of Science:

• Hepatology
• Biochemistry
• Clinical Nutrition

Background:

• Hepatic encephalopathy is a serious complication of cirrhosis.
• The role of specific neurotoxins like tyramine in hepatic encephalopathy pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the association between plasma tyramine concentrations and hepatic disorders, particularly hepatic encephalopathy.
• To assess the impact of dietary protein on tyramine levels in cirrhotic patients.

Main Methods:

• Radioimmunoassay was used to measure plasma tyramine concentrations in healthy subjects, patients without liver disease, and cirrhotic patients (with and without hepatic encephalopathy).
• The effect of increased dietary protein (40 to 80 g/day) on tyramine levels was evaluated in cirrhotic patients.
• Plasma tyrosine concentrations were also measured and correlated with tyramine levels.

Main Results:

• Plasma tyramine levels were significantly higher in cirrhotic patients with hepatic encephalopathy (6.4 +/- 0.1 ng/mL) compared to healthy subjects (1.3 +/- 0.1 ng/mL) and cirrhotic patients without encephalopathy (2.7 +/- 0.5 ng/mL).
• No significant difference in tyramine levels was observed between healthy subjects and patients without liver disease.
• Increasing dietary protein intake led to a 30-70% increase in fasting tyramine concentrations within three days in both encephalopathic and non-encephalopathic cirrhotic patients.
• Plasma tyramine concentration was significantly correlated with plasma tyrosine concentration (P < 0.001).

Conclusions:

• Elevated plasma tyramine is a significant biochemical marker associated with hepatic encephalopathy in cirrhotic patients.
• Dietary protein intake directly influences tyramine levels, suggesting a potential therapeutic target for managing hepatic encephalopathy.
• Tyramine may play a role in the neurotoxicity observed in hepatic encephalopathy.