The kidneys are vital organs. Their main task is to produce urine. Our body can excrete toxic (urinary) substances via the urine. However, kidney function can slowly decline over the course of a lifetime due to various triggers.
Here you will find all the information you need about renal insufficiency and selected medical specialists.
Doctors refer to this development as chronic renal insufficiency (CRF)or chronic kidney failure. This must be distinguished from the sudden cessation of kidney function. This is known as acute renal failure (ANV). Renal insufficiency or kidney weakness leads to a number of secondary diseases and symptoms. These ultimately lead to death in the event of total loss of kidney function without treatment.
People with terminal renal insufficiency always require dialysis and can only improve their quality of life in the long term through a kidney transplant (kidney donation). But what are the main tasks of the kidneys? Can they do more than just produce urine?
The most important tasks of the kidneys in the body:
The kidneys form a very important filtering station within the human blood circulation . They receive their blood via the renal artery. Within the kidney, this artery divides into smaller and smaller blood vessels, which ultimately form a capillary ball. These smallest blood vessels with the smallest diameter are called glomeruli, which means ball in Latin.
Each kidney has more than one million of these glomeruli in its so-called renal cortex. The glomeruli in turn are surrounded by the finest urinary tubules. The blood is filtered out of the vessels through the thin capillary wall of the glomeruli. It enters the urinary tubules as so-called primary urine. This process produces up to 180 liters of primary urine every day! However, only 1 to 1.5 liters are released per day. But what happens to the rest of the filtered primary urine?
The solution to the mystery is reabsorption. In the tubule structures adjacent to the glomeruli, the final urine is formed from the primary urine in several steps. This final urine ultimately flows out via the ureters, bladder and urethra. The original 180 liters of primary urine are concentrated to around two liters of urine per day through the reabsorption of minerals and water.
If the kidneys are not working properly, it is not just urine production that is affected. Rather, the effects of renal insufficiency can be seen in a number of other organs. Oedema can form due to the lack of water excretion from the body. This occurs primarily in the legs, abdomen and lungs.
In addition, people with chronic kidney failure often suffer from high blood pressure (hypertension). Arteriosclerosis is a particular risk for renal insufficiency. If the body's blood vessels become increasingly constricted by deposits, this can also lead to high blood pressure. It can also lead to damage to the fine renal capillaries in the glomeruli. Very often, arteriosclerosis also leads to coronary heart disease.
If renal insufficiency develops, the body no longer excretes urinary substances and toxins sufficiently. As a result, it slowly poisons itself. Chronic kidney failure therefore also leads to damage to the brain, individual nerves and muscle tissue as it progresses.
In addition, the immune system is overwhelmed by the toxins and works to a significantly limited extent. The concentration of urinary substances can be regulated by adjusting the diet. As a result, people with kidney failure are often much more susceptible to illness. Renal insufficiency can already lead to anemia.
Anemia is also typical in dialysis patients. These are patients who are already at a very advanced stage of renal insufficiency. Anemia develops because an impaired kidney produces less erythropoietin, a hormone that stimulates the formation of red blood cells (erythrocytes).
Renal insufficiency indicates the slow loss of kidney function. The term insufficiency means that the kidneys are no longer doing their job adequately; in short, the kidneys are no longer performing well enough. The word chronic in turn means that the destruction of the kidney tissue continues to increase over the years.
The causes of chronic kidney failure are
Chronic kidney failure develops slowly and progresses in different stages, which allow doctors to classify patients.
Chronic kidney failure usually develops slowly in five stages, which are differentiated according to the severity of the disease. The higher the number of stages, the more advanced the chronic renal failure.
The classification of the stages is not arbitrary, but is based on a laboratory value measured in the patient, the so-called glomerular filtration rate (GFR). The GFR indicates how well the kidneys are able to excrete urinary and toxic substances.
If the excretion of these substances no longer functions adequately, the urinary substances accumulate in the blood. As these often act as toxins, they increasingly impair the functions of other organs in the body. But what are all urinary substances? Urinary substances include, for example
Chronic renal insufficiency or chronic renal failure essentially develops along the following parameters:
compensated stage: with an initial slight restriction of filtering capacity, the creatinine level in the blood is initially still normal.
The normal GFR value for creatinine is between 95 and 110 ml per minute. A healthy kidney therefore removes at least 95 ml of creatinine from the blood every minute, which can then be excreted in the urine. If this value is significantly undercut, the creatinine value in the patient's blood also rises.
Measuring the GFR is of vital importance. It allows renal insufficiency to be diagnosed at an early stage and treatment or therapy to be initiated. If only the creatinine in the blood were determined, it would only be possible to recognize much later that the kidneys were working incorrectly. In detail, the 5 stages of renal insufficiency are defined as follows:
The GFR is still greater than 90 ml/min.
This value indicates that the kidneys are still functioning normally. Initially, the blood levels of urinary substances are still within the normal range. In some cases, protein is excreted in the urine at the onset of renal insufficiency. In stage 1, it is important to find out why they are no longer working fully.
If the cause of the disease is finally treated, further deterioration can still be prevented at this stage of renal insufficiency. The diagnosis of renal insufficiency in this initial stage is often only an incidental finding, as those examined do not yet have any symptoms.
The GFR tends to be between 60 and 89 ml/min.
Even in stage 2, kidney failure is not always easy to diagnose. A blood test can provide initial indications. The kidneys are still working adequately. However, a more detailed nephrological examination quickly reveals deficits in the GFR.
High blood pressure and diabetes are the two diseases that can regularly lead to kidney damage. Rapid treatment or therapy of these diseases is important in order to halt the progression of renal insufficiency. Particular attention must also be paid to diet, especially in the case of diabetes.
The GFR drops to 30 to 59 ml/min.
The kidney damage is more advanced and there are increased creatinine and urea levels in the blood. Symptoms of renal insufficiency appear: Those affected suffer from high blood pressure (hypertension), loss of performance and fatigue. These symptoms are usually still far too unspecific to indicate a problem with the kidneys.
At this stage, the risk of cardiovascular disease is also significantly increased. Medications that are normally excreted via the kidneys must be dosed lower so as not to provoke side effects.
The GFR falls to 15 to 29 ml/min.
The renal insufficiency continues to develop and at the same time the symptoms increase: Sufferers experience loss of appetite, vomiting, nausea, nerve pain, itching and often bone pain. The body excretes fewer salts and less water. This leads to water retention in the tissues. Edema forms, e.g. on the legs or face.
In stage 4, the damage to the kidney cells is already very extensive. The entire body is affected by the inadequate excretion of urinary substances. However, the symptoms of renal insufficiency are not caused solely by the accumulation of toxins. Rather, impaired kidney function is accompanied by the loss of important hormones and minerals.
One cause of fatigue, for example, is a lack of red blood cells. In addition to its function as a filtering system, the kidneys produce hormones and messenger substances. Erythropoietin (EPO), which is often used as a doping agent in sport, increases the formation of red blood cells. Without them,less vital oxygen reachesthe body's cells, reducing their performance.
From stage 3 at the latest, a kidney specialist must be involved in the treatment. Medication and a change in diet and drinking habits can slow down the progression of renal insufficiency. When eating, close attention should be paid to the consumption of protein. However, as soon as the medication is not taken or even infections affect these organs, the renal insufficiency progresses further.
The GFR falls below 15 ml/min.
If they finally fail completely, the nephrologist speaks of terminal renal insufficiency. This is stage 5 renal insufficiency and rapid countermeasures are then absolutely essential, as otherwise the body will quickly poison itself. Various methods are available to filter urinary substances:
In general, there are far too few donor kidneys available for the many dialysis patients. Long waiting times for a kidney transplant are therefore unavoidable. Alternatively, a kidney transplant can be planned before stage 5 if a living donor from the family circle is a possible donor.
Despite up to daily dialysis, terminal renal failure has an impact on the body. Yellowing of the skin or increased itching can occur. Both are due to the storage of urinary substances in the skin. There are also other problems with terminal renal insufficiency, such as
This shows that even regular dialysis cannot completely replace kidney function. On the other hand, people with end-stage renal disease cannot survive without dialysis.
People with chronic kidney failure have a significantly increased risk of stroke. They also have a poorer prognosis after a stroke compared to healthy people.
Overall, chronic renal failure is about twice as common today as it was ten years ago. In industrialized nations, the rate of renal insufficiency is between 10 and 20 %. Among patients aged 70+, it even reaches almost 40 %. This high prevalence also has an impact on the stroke rate. For example, the risk of stroke increases threefold with a glomerular filtration rate (GFR) of less than 30 ml/min. In people on dialysis, it even increases six-fold.
Even after surviving a stroke, people with chronic renal insufficiency are worse off: two years later, on average up to 15% of patients without kidney failure have died, but over 40% of those with renal insufficiency. Patients who required hemodialysis even died in over 60% of cases.
Up to three quarters of stroke patients with end-stage renal disease are dead after two years. Of those without dialysis, this applies to just over half. In contrast, the two-year mortality rate for healthy kidneys is only around 30%. These data are confirmed by a registry analysis of over 132,000 patients with atrial fibrillation (AF): this showed that people with renal insufficiency had a significantly higher risk of thrombotic infarction, but also of bleeding.
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