Stages of Chronic Kidney Disease

As a physician and chief medical officer at the StayWell Health Center in Waterbury, Connecticut, Dr. Rex Mahnensmith draws on more than 40 years of clinical practice experience. Dr. Rex Mahnensmith served for 20 years as medical director of dialysis and clinical director of nephrology at the Yale Medical Group, through which he treated numerous patients with kidney disease.

The course of chronic kidney disease involves five stages, which differ based on the kidneys' level of function and the amount of protein in the urine. Clinicians determine the former by testing the glomerular filtration rate, or GFR, which is defined by the amount of blood that the nephrons of the kidney can filter per minute.

A person with mild symptoms of kidney disease but normal or better GFR (90 percent or greater kidney function) receives a classification of Stage 1, which suggests potential kidney damage but normal levels of kidney function. Stage 2 correlates with a reduced GFR and 89 to 60 percent kidney function.

As GFR drops and kidney function decreases, the patient progresses through Stages 3a, 3b, and 4. A patient with Stage 5 chronic kidney disease, also known as end-stage kidney disease, has complete or near-complete loss of function, to the degree that there is a dangerous accumulation of water and waste in the blood. This causes a variety of symptoms including headache, cognitive disturbances, digestive distress, and changes in skin color.

Patients who reach Stage 5 chronic kidney disease typically need intensive treatment in order to survive. This may take the form of dialysis or a kidney transplant.