Is it okay?

I think that there is a difference regarding removal of toxins through water from urination and perspiration. I do believe that urination tends to eliminate much of the toxins than perspiration. Also, I do think that perspiration works more towards the balance of heat in your body so it may function more solely on maintaining the right body temperature rather than mainly eliminating toxins in the body. Also, try to check the urine color for the details whether you are hydrated or dehydrated. That will be a good indication of the amount of water you need to drink in order to stay healthy and hydrated.

A person who has no kidney or bladder disorder should at least urinate 34 ml for every hour. In other words, at least 816 ml a day. Those who have more weight must have more urine output, 36 ml and up per hour. However, don't worry if you do not urinate every hour, because if one has a big bladder, it could hold the urine for more than two hours. What is important is that you must have a urine output of 816 ml to 2,000 ml in a 24-hour duration.

If you go to the toilet the colour of your urine should be like water. If it's coloured dark you drank too less. How long someone can hold in has also to do with the size of the bladder! Some people have a small bladder other people a big(er) one. Holding your pee is bad if you feel pain or can't really go to the toilet in a normal way later (lost the pressure/feeling). It's also better not to hold it in and go more frequently if you have easily infections. The shorter bacteria stay in your bladder the better it is then. Drinking too much can harm your kidneys because extra drinking is extra work is getting damaged earlier. If you have a ICP it might be smart to hold in for longer. Why? Because all the scarves inside your bladder will make it smaller and smaller so in the end you are not able to keep the urine inside anymore. So it depends on you as a person, your lifestyle etc how frequently you go to the toilet. With healthy people it will arrange itself. If you don't find the time to go to the toilet at day time because you are way too busy you will probably go as soon as your body is resting (at night).

Its not the same. Excretion of urine get rids of more metabolic waste products as well as other components filtered by the kidney. Whereas Perspiration or sweating is a secretion process not excretion therefore it has not to do with kidneys. Although sweat also contains minimal amount of metabolic products. If you feel like urinating do it. Don't hold back because it might cause urinary tract infection which if not treated can result into further damage in your kidneys.