I am so sorry to hear that your sister is in the hospital and that she is now dealing with Lupus Nephritis. There are many here who also deal with that same issue. I am going to give you some websites/pages to read in order to provide you with more information on this illness. Please know that we are here to help you and your sister as much as we can.
Lupus Foundation Of America (see kidney diseases)
I wish you and your sister the very best.
Peace and Blessings
Look For The Good and Praise It!