Which ketone is primarily detected in urine testing related to fat metabolism?

The primary ketone detected in urine testing related to fat metabolism is acetoacetate. During the process of ketogenesis, especially in conditions where fat metabolism is significantly increased (such as fasting, prolonged exercise, or diabetic ketoacidosis), acetoacetate is produced from the breakdown of fatty acids.

While beta-hydroxybutyrate is another significant ketone body formed during this metabolic process, it is less likely to be detected in urine compared to acetoacetate, which is why acetoacetate is the main focus for urine tests related to fat metabolism.

Acetone is also a ketone that can be found during fat metabolism but is less abundant in urine than acetoacetate. Propionic acid, on the other hand, is not a ketone; it is a short-chain fatty acid produced in the metabolism of certain amino acids and is unrelated to the direct process of fat metabolism that forms ketone bodies. Therefore, acetoacetate is the most relevant ketone body detected in urine tests for fat metabolism.