Hi lion, I'm sorry I don't know much about
the ketone test. Are you also monitoring your blood sugar? There are various reasons why ketones would be present, anything from a very low carb diet, gestational diabetes, very high blood glucose,.... A lot depends on if your blood sugar is high or in the normal range. I think you should call your doctor. And drinking lots of water is good from what I understand. Let us know how this goes.
I just realized one of your medicines, prednisoloe, might be affecting your blood sugar. Is that why you took the glucose tolerance tests?