alphahydroxybutyrate

Alpha-hydroxybutyrate, commonly called 2-hydroxybutanoic acid (IUPAC name) or 2-hydroxybutyrate in salt form, is a four-carbon alpha-hydroxy carboxylic acid with the formula C4H8O3. It occurs endogenously in humans as a metabolic intermediate linked to amino acid catabolism and energy metabolism.

In human metabolism, alpha-hydroxybutyrate is primarily derived from alpha-ketobutyrate. Alpha-ketobutyrate itself arises from the catabolism of threonine and from the transsulfuration pathway that processes homocysteine to cysteine. Under certain conditions, alpha-ketobutyrate can be reduced to 2-hydroxybutyrate, or it can be oxidized and funneled into propionyl-CoA and subsequently succinyl-CoA, feeding the citric acid cycle.

Physiological role and interpretation of levels are primarily as a metabolite rather than an essential substrate. Plasma and urine concentrations of 2-hydroxybutyrate are influenced by the body's redox state and by the demand for glutathione synthesis; increases have been observed in contexts of oxidative stress and altered sulfur amino acid metabolism.

Clinical and research relevance centers on its use as a potential biomarker. Elevated 2-hydroxybutyrate has been studied as an early indicator of insulin resistance and metabolic risk in some populations, though findings are not universally consistent. Measurement is typically performed using targeted metabolomics methods, such as LC-MS or GC-MS.

Safety and handling follow standard laboratory practices for small-molecule organic acids; it is generally regarded as a normal metabolic intermediate rather than a hazardous substance.