What does it mean to have ketones in your urine?

Dehydration. It is generally a sign of dehydration. If you have diabetes, it can be a sign of diabetic ketoacidosis (too high a sugar level). It can be present in alcoholics with poor nutrition recently (alcoholic keto-acidosis) and in people who have not eaten lately (starvation keto-acidosis).
Sometimes diet based. Agree with the above answers but must add that I see many patients these days with ketones in their urine which is due to specific dietary choices. The "ketogenic" diet is a very popular diet and is similar to atkins style diets of very low carbohydrates. These diets lead to ketones in the urine.

Related Questions

What does it mean when you have leukocytes and ketones in your urine?

Urine results. Leukocytes/white blood cells indicate that inflammatory/infectious process is occurring, especially if rbcs are not present to support the idea of whole blood in the urine. Ketones are breakdown products of fats/fatty acids & seen in fasting or starvation. Lab findings must be taken in a clinical context; we would need to know what symptoms, issues, or other info available if any to help evaluate. Read more...