Ketoacidosis is a type of metabolic acidosis which is caused by high concentrations of ketone bodies, formed by the deamination of amino acids, and the breakdown of fatty acids.

Ketoacidosis occurs when cells do not have sufficient glucose to meet their metabolic demands. Instead, ketone bodies are produced for energy via the metabolism of fatty acids. Acidity results from the dissociation of the H⁺ ion at physiological pH of metabolic ketone bodies such as acetoacetate, and β-hydroxybutyrate.

Ketoacidosis should not be confused with ketosis, which is one of the body’s normal processes for the metabolism of body fat. In ketoacidosis, the accumulation of keto acids is so severe that the pH of the blood is substantially decreased.