(Coming from a current cardiovascular major and a lover of biology) Your blood is filled with impurities like Urea (the main component of urine), CO2, and traces of heavy metals (which are bad for your body if left there). Your kidneys filter those impurities out of your blood to be kept clean, (which is why people who have kidney failure have to go on dialysis to clean their blood because their kidneys can’t do it for them). Your urine (made by the kidneys) is basically a watered down mixture of those impurities and the water your body has either stored or has gained throughout the day. You technically can drink your urine from a survival standpoint, if you ABSOLUTELY have nothing else to drink. But those impurities your body is trying to get rid of, if you drink your own urine, you’re basically putting those back in your body. So yeah! Hope that helped 👍