Chronic renal failure: Now more commonly classified as chronic kidney disease and is listed as stages based on the patient's level of glomerular filtration rate (GFR) which is a measure of filtering capacity of the kidneys. Stage 1 means normal filtering function of the kidney but delineates those patients that are at risk of progressive renal disease, such as those with proteinuria or hematuria. Stage 2 is used for patients with a GFR of 60 to 90 mL per minute. Stage 3 is used for patients with a glomerular filtration rate of 30 to 60 mL per minute. Stage 4 is for patients with a glomerular filtration rate of 15 to 30 mL per minute. Stage 5 is for patients with a glomerular filtration rate of less than 15 mL per minute but who are not on dialysis. Stage 6 is for patients who have a glomerular filtration rate of less than 15 mL per minute and require dialysis intervention for their renal failure. Chronic kidney failure or chronic renal failure signifies loss of kidney function that occurs over a prolonged course of time as opposed to acute renal failure. The loss of renal function may be due to previous episodes of acute renal failure with subsequent long term kidney damage or may be due to diseases which cause progressive deterioration of the kidney such as primary kidney diseases (glomerulonephritis) or secondary disorders such as diabetes, hypertension, or auto-immune disorders. The loss of kidney function may be progressive but with therapy of the underlying cause the damage can be halted and in some cases the kidney function may actually improve. Unfortunately, many patients with chronic kidney disease, especially if they reach Stage 4 or Stage 5 will progress to point of end stage renal disease (ESRD) which is the point of needing dialysis or renal transplant. If the patient is started on dialysis, this is synonymous with chronic kidney disease Stage 6. Much work is being done to try to help halt or slow the progression of chronic kidney disease. The ability to diagnose early chronic kidney disease is very helpful in being able to prevent the progression of the patient's kidney deterioration. Slow progressive loss of kidney function over the span of years resulting in permanent kidney failure. Chronic kidney disease is common and may go undiagnosed until the process is far advanced and renal failure is on the horizon. People with permanent kidney failure need dialysis or a transplanted kidney to do the work of their failed kidneys.