Yes, my kidney disease is caused by my lupus. When I was first diagnosed with kidney disease I felt perfectly fine! The only reason I went to the doctors was because I retaining fluid and couldn't get rid of it. My GP couldn't find anything wrong with me but she did do a urinalysis and sent it to the lab. It was my urine that showed 3+ protein and I was told I had kidney problems. That shocked me, and then my neph said he thought it was lupus. I was really shocked then!!!! My biopsy came back as "these findings raise the question of lupus nephritis." However, I didn't meet the criteria and felt great so my neph called it idiopathic membranous. During the course of the next 2 years I started having lots of lupus symptoms so I was sent to a rheumy. He diagnosed me with lupus and 2 more nephs have said definite lupus. There is no history of lupus or kidney disease anywhere in my family. I do not have any risk factors either, and my blood pressure has always been low. Like you, I just seemed to have kidney disease one day.
I admire you tackling medical school. It is hard enough for any one and you are sick on top of that. Keep your positive outlook and good luck with your tests. Keep us updated in the lupus forum. I know you pop in there and have given some great advise. We appreciate it!