b-Aminoisobutyric Acid

Elevated levels may be associated with increased intake of the precursor amino acid valine. Levels are higher with exercise. 

A functional need for vitamin B6 can also contribute to elevations.

Clinically, transient high levels have been observed under a variety of pathological conditions including lead poisoning, starvation, total body irradiation, and malignancy.

Low levels of β-AIB may be seen with decreased precursors, such as valine. Dihydropyrimidine dehydrogenase deficiency is a rare inborn error of metabolism that results in lower levels of urinary β-AIB.

Beta-aminoisobutyric acid (also known as 3-aminoisobutyric acid) is a non-protein amino acid formed by the catabolism of valine and the nucleotide thymine. It is further catabolized to methylmalonic acid semialdehyde and propionyl-CoA.

Levels are controlled by a vitamin B6-dependent reaction in the liver and kidneys.

β-aminoisobutyric acid can also be produced by skeletal muscle during physical activity.