Our seven month grandson was diagnosed with a Wilms tumour on one kidney. After major surgery to remove the tumour, the kidney and 5 months of chemo, he is on 3 monthly check ups and doing well. It is no problem to have one kidney as it is perfectly capable of coping...think how many people donate their kidney and the other one takes over. The only thing we have been told is no boxing....but I am more than happy that he never boxes in his life! It may be that your grandaughter will need regular checks. Certainly our little grandsons one kidney is working perfectly. I hope the referral is reassuring for you all. Let me know. Xx