Glomerular Filtration Rate (GFR): Your GFR tells how much kidney function you have. It may be estimated from your blood level of creatinine. If your GFR falls below 30 you will need to see a kidney disease specialist (called a nephrologist), Your kidney doctor will speak to you about treatments for kidney failure like dialysis or kidney transplant. A GFR below 15 indicates that you need to start one of these treatments.
Stage Description Glomerular Filtration Rate GFR)At increased risk Risk factors for kidney disease (e.g., diabetes, high
blood pressure, family history, older age, ethnic group) --- >> More than 90
1 Kidney damage (protein in the urine) and normal GFR --- >> More than 90
2 Kidney damage and mild decrease in GFR --- >> 60 to 89
3 Moderate decrease in GF --- >> 30 to 59
4 Severe decrease in GFR --- >> 15 to 29
5 Kidney failure (dialysis or kidney transplant needed) --- >> Less than 15
This is from National Kidney Foundation -- more info here
http://www.kidney.org/kidneydisease/ckd/knowGFR.cfm