Used in diagnostic testing for metabolic disorders, particularly ethylmalonic encephalopathy, a rare genetic condition. Elevated levels of ethylmalonic acid in bodily fluids like urine or blood serve as a biomarker for impaired mitochondrial fatty acid oxidation and organic acid metabolism. It helps clinicians identify defects in short-chain acyl-CoA dehydrogenase (SCAD) activity. Also used in research settings to study mitochondrial dysfunction and oxidative stress in cellular models. Its accumulation is associated with neurological symptoms, making it relevant in neurochemical studies.