What is the Alpha-ANB/Leucine Ratio? High and low values | Lab results explained

Also known as: Alpha-Amino-N-Butyric Acid to Leucine ratio

Alcohol consumption can result in elevations of the plasma Alpha-ANB/Leucine ratio. But to see this biomarker as a conclusive marker for alcoholism is not proven. The increase in the plasma Alpha-ANB/Leucine ratio does not appear to be specific for alcoholism because it was found elevated in nonalcoholic liver disease.

It is most likely that the rise in the plasma Alpha-ANB/Leucine ratio identifies a subgroup of alcoholics. What determines this subgroup of alcoholics remains unclear, but it could be the quantity of alcohol intake, a nutritional deficiency, or the presence of liver disease.

Higher levels:

The Alpha-ANB/Leucine ratio can be a marker for alcoholism. Elevations of this amino acid are seen in some alcoholics, but it does not appear to be specific for alcoholism because it was found elevated in nonalcoholic liver disease.

Elevated plasma Alpha-Amino-N-Butyric Acid indicates vitamin B6 insufficiency since this amino acid is metabolized via the usual hepatic transamination reaction requiring pyridoxal phosphate. 

In a study the Alpha-ANB/Leucine ratio was also elevated in children with Reye’s syndrome, tyrosinemia, homocystinuria, nonketotic hyperglycinemia, and ornithine transcarbamylase deficiency. The results indicate that an elevated ratio is not specific for adults with alcoholic liver injury and that the ratio may be high even without the presence of clinically apparent hepatic disease. An altered ratio may reflect the presence of an inherent metabolic defect.

References:

• Plasma alpha-amino-n-butyric acid/leucine ratio in alcoholics. (L)
• On the clinical significance of the plasma alpha-amino-n-butyric acid:leucine ratio. (L)
• Plasma alpha amino-n-butyric acid to leucine ratio: an empirical biochemical marker of alcoholism (L)
• Ratio of plasma α-amino-n-butyric acid to leucine in alcoholism (L)