A problem with measuring hydration by ketone reading is that yOur ketone reading can be quite high without you being dehydrated. Hydration, level of ketones in the blood, and level of reabsorption by the kidneys are the main factors. I have also seen the idea around that as we become ketone and fat adapted, ketones disappear,sometimes put in terms of us using the ketones instead of spilling them. This is truthy, certainly if we absorb them less are wasted, more burned, but we burn them because they are available, not having been spilled, rather than them not being there to waste due to being burned. From the idea that adapted people spill less ketones sometimes I see people worried that showing ketones means they are not well adapted, that is just one more false conclusion that cannot be supported by a urine ketone reading.