If ketone levels are very high or if the person is dehydrated, ketones may begin to build up in the blood. High blood levels of ketones may cause fruity-smelling breath, loss of appetite, nausea or vomiting, and fast, deep breathing.

Why does dehydration cause ketones in urine?

If for any reason the body cannot get enough glucose for energy it will switch to using body fats, causing an increase in ketones in the body. This results in more ketones present in the urine.

Does hydration affect ketone levels?

Hydration can affect the concentration of ketones in your urine, which may give an incorrect reading. Although the urine strips aren't precise, they can give you an idea whether you're eating too many carbs. Blood ketone tests provide better results.