Does dialysis happen when the kidneys completely shut down or when they're still functional to some degree?

Dialysis. Dialysis usually starts before the kidneys completely shut down. Renal function (GFR) is measured on a scale of 60 to 0, and dialysis usually starts around a level of 15-10. For successful dialysis early planning is important. The shunt (vascular access) needs to be put in at least 6 months before intended use. Most affected persons should see a nephrologist by time their GFR is in the 30-20 range.