no it cannot cure anything!!! It is good for you to use yoga as a tool to help you maintain a healthy lifestyle and can even make dealing with debilitating arthritus pain, a bit less intesne but there is not a way to say excercise is going to cure a diesease in the body.

Please go to the doctor and get a medical protocol started for your treatment regimene and also while talking to your doctor, bring in your own yoga regemine and show them how you are going to maintain a healthy lifestyle. It may make the difference with the way they treat your disorder.

Yoga is great for stress relief, especially the meditation part of the pracitce (known as 'savasana'). This would then help any stress-related kidney problems.
Also, many yoga poses involve toning the abdomen & the inner organs, such as twists, inversions, and core strengthening poses.
But yes, definitely check with your doctor before beginning any major exercise program. Yoga is fantastic but, as with any health care, it can injure you if you don't know what you are doing.

and water! both help, i know the pose but not the name, you sit on your knees, and bend your body back