Alpha-Aminobutyric acid Test

Alpha-aminobutyric acid (AABA) is a small amino acid that is not normally built into proteins but instead circulates in the blood as part of various metabolic processes. Unlike essential amino acids, which must come from diet, AABA arises mainly as a byproduct of other amino acid pathways, particularly those involving methionine and threonine. Because it reflects underlying shifts in metabolism, researchers have started to view AABA as a window into health and disease.

In healthy adults, higher levels of L-AABA have been associated with better physical performance, including faster walking speed and improved measures of mobility. This relationship appears especially strong in men, and researchers believe it may capture aspects of muscle and neuromuscular health that change with age. The ratio between gamma-aminobutyric acid (GABA, a neurotransmitter that calms the nervous system) and AABA has also been suggested as a marker of aging, since it relates to both brain and muscle function.

AABA has clinical relevance beyond physical performance. In patients with liver disease, especially cirrhosis, abnormal AABA levels have been linked to malnutrition, impaired bone health, and even risk of variceal bleeding, which is a dangerous complication where swollen blood vessels in the esophagus rupture. In these cases, measuring AABA alongside other metabolites such as citrulline can help doctors noninvasively estimate risk and disease progression. Importantly, only the L-form (enantiomer) of AABA is found in human serum, which simplifies its use as a biomarker compared to some amino acids that exist in multiple forms.