Okay, when you thought you went through the change, did you go to the gyno and get blood work done to confirm that it really was menopause? Because kidney failure, especially the anemia part of it, can stop your periods without it really being the hormonal shift that comes with the change. If you stopped because of anemia or the chemical changes in your system from ESRD (especially during the pre-dialysis stages), then once you have the chemical cleaning and rise in hemoglobin that comes with adequate dialysis and treatment for anemia, there's no reason your body can't and won't start your cycle again.
Having terrible, heavy periods when being exposed to heparin is a pretty common symptom for ESRD women who are not menopausal. Check out this discussion of possible treatment options to help if the cat scan shows no other issues:
http://ihatedialysis.com/forum/index.php?topic=23342.msg379695#msg379695 And you might want to consider checking in with your gyno if you haven't already. Nephs, especially male ones, tend to be pretty clueless about this aspect of dialysis for women!