Ketones also show when your body begins to metabolize fats and proteins for energy instead of carbohydrates. Can be a sign you aren't eating enough. High ketones can cause damage to your kidneys and to your developing babys brain and kidneys.
They'll most likely put you on am iv for fluids. Ketones are found in urine when you're dehydrated. I had HG with my first pregnancy and once a day I'd have to pee on a stick that measured ketones in my urine, if it was higher some days they would make me drink an extra 2 or 3 water bottles or go in for iv fluids. Stay hydrated!! Goodluck! :)