Which condition could result in a sweet odor in urine due to the presence of ketones?

The presence of a sweet odor in urine due to ketones is primarily observed in the context of starvation. During periods of starvation, the body depletes its glycogen stores and begins to metabolize fatty acids for energy. This process results in the production of ketone bodies, which include acetoacetate, β-hydroxybutyrate, and acetone. The accumulation of these ketone bodies in the bloodstream can lead to ketoacidosis, especially if the individual has prolonged fasting, thus causing the urine to exhibit a distinct sweet or fruity odor as the ketones are excreted.

In contrast, conditions such as tyrosinemia, phenylketonuria, and maple syrup urine disease are associated with abnormal amino acid metabolism and can lead to characteristic odors, but they do not produce ketones as a primary metabolic by-product. Therefore, while those conditions may have their own unique urinary odors, they do not cause the sweet taste linked specifically to ketone presence like starvation does.