Anybody have to get a nephrologist clearance?

I'm scheduled for a revision from VBG to RNY on 11/8/10.  One of the lab work came back abnormal, creatinine was 7.8, so surgeon said I had to have a nephrologist clearance.  I see the nephrologist Monday.  I don't know yet if I have to reschedule the surgery.  But I was wondering if anyone else had to have a nephrologist clearance?

My primary doctor thinks it is just because the surgeon has me on a high protein pre-op diet and I haven't got enough fluid in and that's why it is elevated.  I also have hx of high creatinine in the past(2.4, 2.5), but when they done the 24hr urine creatinine clearance they were normal.  So I've been making sure that I drink, drink, and drink some more.

Can anybody share their experience with this situation, if they have a similar experience?

Thanks

Dorothy