Which would be safer?

In your opinion, do you think it would be safe to remove one kidney that is functioning 0% and leave someone with the other kidney that is only functioning 70% that needs microvalve surgery as well or do you think it's safer to wait and do both surgeries at the same time to give them a better chance of having the good kidney stronger from the repair so it can do the job of both rather than risking the possibility of it failing as well and putting her in greater danger than she was at the beginning.

[ed34]

That is a very difficult question and one which would really require a lot more information to answer, such as the general condition of the patient especially lung function and heart condition. However if one had to look at this based on logic alone and taking it the patient is healthy in all other aspects I would look at it this way....

If one kidney has failed it has no use at all, even if the good kidney fails, the dead one will have no use.
The good kidney is working at 70% and requires surgery. I am not sure whether 70% of
kidney function is enough for the body as I know little about them, but it doesn't sound like it is. So, surgery is necessary. Each time a patient is put under general anaesthetic they are put at risk and post surgery there is always a risk of infection.

To me this is a bit like saying "you need a triple bypass but we will graft on vessel today, then next month we will open you up again to graft the second and the month after that we will open you up again to graft the third. We feel this is necessary to ensure each vessel has time to adapt".

I would have both kidneys done at the same time because one is just a removal. Whether removed or not, it is not going to help anyway.