If your blood
Sugar issues are diabetes, then you should address that immediately in regards to your kidneys. Safest route is exercise, as taking large amounts of chromium or vanadium and some of the other blood
Sugar regulators can be harsh on the kidneys.
Salt can be harsh on the kidneys, and I would limit it.
If you think you might have stones, then look into chanca piedra.
As far as diuretics, the best that I have tried is corn silk tea. It is gentle but effective, and has a demulcent quality. It seems to be somewhat kidney-specific in its actions, and is a good all-around therapy for them. Many herbal diuretics can be pretty harsh. I don't think the
kidney cleanse you are looking into is a good idea at all, and I would not recommend it.
Some people find slippery elm tea and marshmallow tea to also be soothing.
Lower back pains could be a lot of things, so hard to give input there. Get some ph paper and start paying attention to urine ph. See if there is any correlation with that and your back pains.
Taurine is very therapeutic to the kidneys. I also take renafood.
Androgens build up the kidneys, although I have seen very little information on this outside of comments from a few individuals like Andrew Cutler. That is also the view apparently taken by TCM, or Traditional Chinese Medicine. For men, at least, limiting sex/masturbation for a period of time or at the very least witholding ejaculation during sex/masturbation can help the kidneys to rebuild. Possibly DHEA and pregnenolone can also be of some help.
Another idea from TCM is that kidneys are very sensitive to the cold. So keep them warm. Hot baths can be soothing to them.
I should note that the kidney in TCM is not just the organ, but related organs and some organs in proximity like the adrenals. Just to clarify. :-)
Drink a large amount of water. General rule is half your bodyweight in ounces. You can go over that and it's fine, but drinking way too much can strain the kidneys as well.
Also, be very conscious of chemical exposures. Weakened kidneys can be sensitive to chemicals.
Avoid painkillers such as aspirin or acetaminophen (Tylenol). Harsh on kidneys.
The kidneys are a very fragile organ, so please be very careful with them. Sadly, there is very little good information out there on keeping them healthy. It takes a lot of digging.