@hello1234 Here is an article from Cleveland Clinic about nephrectomy https://my.clevelandclinic.org/health/treatments/21515-nephrectomy

Typically, the native kidneys have indicated they have a problem, which has led to the kidney transplant to start with. With PKD, the native kidneys may indeed lose function, but the cysts continue to cause issues. They can grow in size, and start to cause an issue in the bowel area. If they have no functionalbility left, there is no reason to keep them, then.

Of course your friend is shaken up! Going merrily along your way entertaining a new-to-you kidney, then get this news. If she has concerns, have her write them down and present them to her transplant team. We know our medical teams are not going to do anything to jeopardize the new kidney if they can help it. There must be a reason they are recommending this, and it may set her mind at ease to know why. Also, seeing it is scheduled for a couple of weeks must have her on pins-and-needles, so any info she can find out from them will help. You're a good friend to be there by her side.
Ginger