Chronic renal insufficiency is characterized by a gradual deterioration of kidney function. Depending on the severity, physicians distinguish five stages of renal insufficiency. The criterion for classification is the glomerular filtration rate (GFR). This laboratory value allows a statement about the extent of kidney damage: Usually, the kidneys excrete various degradation products of the metabolism, such as creatinine and urea. The more the kidneys are damaged, the less they can filter out such urinary substances. The toxic degradation products of the metabolism then accumulate in the blood, which impairs the function of important organ systems.
reference value
Healthy kidneys have a glomerular filtration rate of 95 to 110 ml per minute, which means that each kidney filters this amount of blood and cleanses it of urinary substances. As kidney failure increases, this value worsens:
Renal insufficiency – stage 1
In the first renal insufficiency stage, the GFR is still more than 90 ml per minute. The creatinine level in the blood is normal, but there is often more protein in the urine – a sign of a disorder of kidney function. Ultrasound sometimes shows the first pathological changes in the kidneys. Stage 1 renal insufficiency often does not cause discomfort, but it can cause water retention in the tissues (edema) or discolored urine. At this early stage, however, kidney failure is usually discovered only by chance. If the cause of the kidney weakness can be found out and treated, it can counteract a further decrease in kidney function.
Renal insufficiency – stage 2
Renal insufficiency stage 2 is characterized by a GFR between 60 and 89 milliliters per minute. As before, however, there are usually no abnormalities in the blood. Only a targeted examination of the kidney function reveals the disturbed filter performance.
Renal insufficiency – stage 3
In renal insufficiency stage 3, the GFR is between 30 and 59 milliliters per minute. The kidney’s filtering function has now been reduced so much that blood levels of creatinine and urea increase. At least now it comes to complaints: High blood pressure, performance degradation and rapid fatigue occur. The probability for cardiovascular diseases increases significantly. If patients take drugs that are normally excreted via the kidneys, their dose must be reduced to avoid side effects.
Renal insufficiency – Stage 4
If the GFR drops to a value between 15 and 29 milliliters per minute, doctors speak of renal failure stage 4. The significantly reduced kidney function causes more and more complaints such as loss of appetite, nausea, vomiting, fatigue, itching, nerve and bone pain. In addition, increased edema, for example on the legs or face.
Renal failure – stage 5
Renal insufficiency stage 5 with a GFR below 15 milliliters per minute is also called terminal renal insufficiency, ie end stage renal failure. The kidney function is now massively reduced or the kidneys are completely out, that is, they can not cleanse the blood. This task must now quickly take a renal replacement procedure, otherwise the urine-containing substances poison the body: the patient is on a blood wash (hemodialysis, HD), abdominal (peritoneal dialysis, PD) or kidney transplantation dependent.
Since the waiting lists for a donor kidney are long, patients must be prepared for regular dialysis treatment (HD or PD), often over several years. As good as this artificial blood filtering works, it can not completely replace the kidneys: some of the urine-containing substances accumulate in the skin, resulting in a yellowish discoloration and itching. Some patients also develop calf cramps, cognitive disorders, cardiac arrhythmias and confusion as well as unconsciousness. Nonetheless, dialysis is in this last of all Renal stadiums absolutely vital, as long as no donor kidney is available.