Renal insufficiency occurs when the kidneys are not able to function properly, and can no longer adequately filter waste from the body. Renal insufficiency may be acute (acute renal failure) or chronic (chronic kidney disease). The Medical College of Wisconsin reports that kidney doctors (called nephrologists) will often stage kidney disease into five levels; however, the stages are not always universally used.
Stage One
The first stage of renal insufficiency is generally described as the time when a person shows only mild signs of the disease, and has a glomerular filtration rate (called GFR), or 90 percent or better. Some people may even have a normal GFR during this stage. The National Kidney Foundation reports that the GFR is calculated by the doctor, using blood creatine levels (waste products in the blood) and other factors, such as age and race.
Stage Two
During the second stage of renal insufficiency, called mild kidney disease, a person still usually has only mild physical symptoms. However, according to the Medical College of Wisconsin, the GFR in this stage is somewhere between 60 and 89 percent. During this stage, a person may feel a bit fatigued, though there may be no other physical symptoms present yet. Blood pressure may be slightly elevated at this point, but may not require medication.
Stage Three
The third stage of renal insufficiency occurs when the GFR is between 30 and 59 percent. This stage is described as moderate chronic renal insufficiency. Physical symptoms may begin to show during this stage. These include fatigue, and a general feeling of illness. A person may also begin to notice some fluid retention at this time, either around their eyes or even in their hands and feet. There may be urinary changes at this stage, though this symptom does not always appear in everyone this early in the disease.
Stage Four
The fourth stage of renal insufficiency is called severe chronic renal insufficiency and occurs when the GFR is between 15 and 29 percent. The National Kidney Foundation reports that, when a person has a GFR below 30 percent, it is time to see a kidney specialist (nephrologist). While specialized kidney treatments may not be initiated at this point, education about future treatment options should begin. A person in this stage may start to experience appetite changes, and may need to switch to a renal diet (low protein, high calorie). They may also have higher blood pressure, requiring medication.
Stage Five
The fifth and final stage of renal insufficiency is end stage renal failure (ESRD), and occurs when the GFR drops below 15 percent. Physical symptoms at this stage include severe fatigue (anemia is common), weight loss, poor appetite, skin changes and breathing difficulties. This is also the stage at which specialized interventions begin. These include regular dialysis treatments, or even a kidney transplant.
