Under typical physiological conditions, acetoacetic acid exists as its conjugate base, acetoacetate.
The ketone bodies are produced by the liver through metabolism of fatty acids to provide a ready energy source from stored lipids at times of low carbohydrate availability. The three ketone bodies are acetone (2%), acetoacetic acid (20%), and 3-beta-hydroxybutyric acid (78%). A low level of ketone bodies are present in the body at all times. However, in cases of carbohydrate deprivation or decreased carbohydrate use such as diabetes mellitus, starvation/fasting, high-fat diets, prolonged vomiting, and glycogen storage disease, blood levels in- crease to meet energy needs. The term ketonemia refers to the accumulation of ketones in blood, and the term ketonuria refers to accumulation of ketones in urine. The measurement of ketones is recommended for patients with type 1 diabetes during acute illness, stress, pregnancy, or elevated blood glucose levels above 300 mg/dL or when the patient has signs of ketoacidosis.
In diabetic ketoacidosis (DKA) beta-hydroxybutyrate (BOHB), the predominant ketone, is a better indicator of clinical state than acetoacetate. The BOHB/AcAc ratio is normally 3:1. This ratio will increase to 6:1 or 12:1 during ketoacidosis, particularly if there is associated decreased tissue perfusion, metabolic acidosis, and tissue catabolism. All of these will favor reductive metabolism and hence BOHB production. Acetoacetate may increase during therapy for DKA because BOHB is oxidatively metabolized to acetoacetate.
Increase
Diabetic ketoacidosis, prolonged excessive insulin administration in diabetics, prolonged fasting (so-called ketotic hypo glycemia, most common in children aged 1-6 yr), severe carbohydrate restriction with normal fat intake (weight-reducing diets), anorexia nervosa, persistent vomiting, glycogen storage diseases I, III, and VI, branched-chain ketonuria, methylmalonic aciduria, exercise in untrained subjects, pregnancy, stress, postanesthesia.