- any of three compounds, acetoacetic acid, beta-hydroxybutyric acid, or acetone, that are intermediate in the metabolism of fatty acids and that are found in abnormal quantities in the blood and urine during certain pathological conditions, as diabetes mellitus.
- any of three compounds (acetoacetic acid, 3-hydroxybutanoic acid, and acetone) produced when fatty acids are broken down in the liver to provide a source of energy. Excess ketone bodies are present in the blood and urine of people unable to use glucose as an energy source, as in diabetes and starvation
