The presence of ketones (ketone bodies) in the urine indicates that the body does not have enough carbohydrates to meet its energy needs and must produce energy from body fat.
Very high levels of urine ketones can occur in poorly controlled diabetes, where ketoacidosis can develop and lead to coma. Slightly to moderately high levels of ketones can be found in patients engaging in prolonged fasting or following diets that severely restrict the amount of carbohydrates permitted. Positive results are also associated with morning sickness (the nausea and vomiting of pregnancy).
Some medications used to treat high blood pressure, such as Captopril© and others (Mesna, etc.), can produce a false negative result.