Stages of chronic renal insufficiency

There are different stages of renal failure is classified differently. There are different ways of classifying chronic renal insufficiency. Chronic renal failure can be classified according to the so-called glomerular filtration rate (GFR) as well as according to the so-called retention values.

The glomerular filtration rate is the value most commonly used for renal function. With this value the individual function of the kidney can be assessed particularly well. A doctor can use the GFR and compare it with standard values to determine whether chronic renal insufficiency is present.

The glomerular filtration rate is a variable that can describe the performance of the kidney. Depending on how much volume can be filtered by the kidneys within a defined time, the individual glomerular filtration rate is determined. In chronic renal insufficiency, this variable, known as GFR, is very low.

If the GFR is less than 15, this is officially referred to as chronic renal failure, while values above 90 indicate normal renal function. However, it is normal for the GFR to decrease over the course of a lifetime, so a disease does not necessarily have to be behind low GFR values. The so-called retention values are also used for classification.

These allow chronic renal insufficiency itself to be divided into four different stages. Chronic renal insufficiency is classified according to how high the substances are in the body that are normally filtered out by the kidneys. In stage 1 of chronic renal insufficiency one speaks of a compensated insufficiency of the kidneys.

Although it can be determined that there is a restriction in the functional performance of the kidneys, the retention values are within the normal range and there are no symptoms. In stage 1 of chronic renal insufficiency, the body can therefore still compensate for the lack of renal function and symptoms that would be associated with increased retention values are therefore absent. The determination of the retention values in the blood is therefore particularly important in the assessment of whether stage 1 or already stage 2 is present.

If the so-called creatinine exceeds the normal level in the blood, at least stage 2 must be assumed, while normal creatinine levels are likely to indicate stage 1 of chronic renal insufficiency. Typical symptoms of renal insufficiency such as water retention/oedema on the legs or face, pulmonary oedema or cardiac arrhythmia are not present in this stage. Stage 2 is defined by the fact that the blood levels are elevated but the symptoms of chronic renal failure do not occur.

The substances that the kidney normally filters out of the blood and excretes with the urine accumulate in the blood in chronic renal failure. The so-called creatinine in particular is examined, which can be used as a reference for the substances to be filtered out. In stage 2 of chronic renal insufficiency, the creatinine present in the blood is increased compared to the norm.

However, the concentration does not exceed values associated with typical symptoms of chronic renal failure. People who have stage 2 chronic renal failure do not suffer from the classic symptoms of the disease, such as water retention or electrolyte balance disorders. The situation is different with stage 3, which is associated with increased retention values in the blood and striking symptoms.

For example, an examination of the blood of a person suffering from stage 3 chronic renal insufficiency can reveal a significant increase in retention values. In addition to a change in the blood values due to the lack of filter function of the kidneys, symptoms of chronic renal insufficiency first become apparent in stage 3. Particularly frequently, unspecific symptoms such as headaches and concentration disorders are initially noticed, but in many cases these are not associated with renal insufficiency.

If water retention on the legs or face, skin symptoms and disorders of the water and electrolyte balance occur, the diagnosis of stage 3 chronic renal failure is quickly made. In contrast to stage 4 of the disease, there is not yet any talk of terminal kidney dysfunction. In stage 3 of the disease, procedures such as dialysis and a kidney transplant are not yet necessary.

In stage 4, the symptoms of the disease are so advanced that terminal renal failure is suspected. Treatment by dialysis therapy is necessary and a kidney transplantation may have to be considered. The substances in the blood, which are normally excreted by the kidneys in the urine, are massively increased at this stage and the functional performance usually causes strong and impairing symptoms.

Especially water retention in the lungs (pulmonary edema) and anemia, as well as severe disturbances of the water and electrolyte balance are classic symptoms of chronic renal failure in stage 4. Regular dialysis treatments are life-supporting measures which become necessary in stage 4. In many cases, a kidney transplant is the only way to get away from the annoying symptoms and dialysis therapy. Not every patient suffering from stage 4 chronic renal failure is assigned a new kidney. Since significantly more kidneys are needed than are available, donor kidneys are allocated centrally.