Professionally, I train a safety segment every year on heat exhaustion that turns into a conversation about how to measure your body's own conditions. Urine can be a great laymen indicator for both your body's hydration level and health.
Urine that is brown, cloudy, or red can indicate that something is going on with the body medically. Liver issues, urinary tract infection, or something else could exist. The amount of times you urinate could indicate either a medical issue or tip you off that you might be consuming too much caffeine.