In a way, yes. Your urine will be more concentrated. However, the specific gravity (hydration level) still varies depending on how hydrated you are. Most of your total water is inside your cells, organs, and tissues. It's not circulating in your blood. So your water intake over the past few days will still be reflected in your first-morning urine specific gravity reading.
To learn more about the science of our test cards, check out our Backed by Science page!