Internal Medicine

Renal failure

Synonyms

Kidney failure, renal dysfunction

English: renal failure

Definition of renal failure

Under one Renal failure one understands the decrease in kidney function (see also: kidney). A distinction is made between the acute Renal failure from the chronic, whereby the former is characterized by a rapid, in principle reversible (rto be undone) Decrease in kidney function, the latter, however, is characterized by a gradual, irreversible (irreversible).

Read on under: Functions of the kidney

Symptoms

Kidney failure can manifest itself through many different symptoms. The main symptom is that decreased urea excretion.
This can lead to a Polyneuropathy (Disease of the peripheral nerves) with impaired sensation and abnormal sensations. Decreased appetite, Hiccups, Headache and vomiting are other symptoms. The build up of urea in the pericardium can cause a Pericarditis trigger. Also Heart failure and cardiac arrhythmias are possible symptoms.

Because the urea no longer or hardly leaves the body, it accumulates in the organism. The too high urea value leads to Acidification of the blood, the urea is then excreted in the exhaled air. The exhaled air has a characteristic odor (foetor uraemicus), and it also occurs Hyperventilation (increased breathing). In severe cases of chronic kidney failure or in acute kidney failure it occurs Drowsiness and confusion or coma with Kussmaul breathing (deep, sighing breathing).

The kidneys produce erythropoietin (EPO), a Hormone that stimulates blood formation. With renal insufficiency it occurs as a result of the lack of EPO Anemia (Anemia) with paleness and tiredness. The kidneys are responsible for activating vitamin D: renal failure leads to Vitamin D deficiency and thus to a breakdown of the bone substance, Bone pain are the consequence.

Other symptoms of kidney failure affect the digestive tract (uremic gastritis or colitis, stomach ulcers), the blood system (decreased function of platelets and white blood cells) or the lungs.

Read more here: Symptoms of renal insufficiency

Symptoms of the skin

In chronic kidney failure, various skin diseases occur.Typical symptoms are calcification of the skin, yellowish discoloration and other pigmentation disorders.
In addition, the number of sebum and sweat glands in the skin is reduced, resulting in dry skin. The reduced excretion of urinary substances impairs the function of the blood platelets: patients with kidney failure often bruise more quickly than patients with healthy kidneys.

Another skin symptom of kidney failure is itching. On the one hand, it is favored by dry skin, and on the other hand, more mast cells are present in the skin in the case of kidney failure. These mast cells are actually involved in allergic reactions. They release the tissue hormone histamine, which gives the skin the feeling of "itching" via the free nerve endings.

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Epidemiology

Acute renal failure occurs 1 to 5% the hospital patient on; more than 10% of patients in intensive care.

In Western Europe, the incidence of chronic renal failure is 10 per 100,000 per year.

Causes of Renal Failure

Acute kidney failure is often caused by circulatory disorders in the kidneys. Examples are circulatory shock from an accident or surgery, a blood clot in the kidney vessels, and certain medications. Long-term lack of oxygen can also lead to acute kidney failure. In addition, obstruction of the urine flow can damage the kidney. An enlarged prostate, urinary stones, inflammation and tumors can obstruct the urinary tract and impede the flow of urine. As a result, acute kidney failure can occur. Chronic kidney failure is caused by diabetes mellitus (diabetic nephropathy) in 35 percent of cases. In addition, high blood pressure is another common cause and at the same time a possible consequence of kidney failure. Various kidney infections, such as glomerulonephritis or interstitial nephritis, can also lead to the development of kidney weakness. Congenital malformations such as cyst kidneys can impair kidney function at an early stage and result in chronic kidney failure. There are also some drugs that can damage the kidneys. These include over-the-counter medicines like acetaminophen, ibuprofen, and diclofenac. These drugs can lead to chronic kidney failure, especially if they are used for a long time.

diagnosis

Acute renal insufficiency: Acute renal insufficiency is first diagnosed with the aid of the anamnesis and the clinical picture including the amount of urine excreted. In addition, blood (including the retention values creatinine and urea; Electrolytes) and urine (Urine status, urine sediment) examined. In addition to the diagnosis of "renal insufficiency", an imaging of the kidneys can be arranged, whereby ultrasound (Sonography, vascular doppler), MRI and CT. The last to be mentioned as a diagnostic means is a kidney biopsy, whereby kidney tissue is obtained for a microscopic examination with the help of a punch.

Read more on the subject at: Urea increased

Chronic renal insufficiency: The diagnosis of "chronic renal insufficiency", like the acute form, is made on the basis of the anamnesis, the clinical picture, the laboratory (blood and urine, see "acute renal insufficiency") and imaging procedures.

Read more on the subject at: Kidney values

Acute renal failure

Acute kidney failure can have various causes. Depending on the cause, patients are either dehydrated (lack of water) or overloaded with fluids (edematous). The kidney values in the blood rise, the urine production decreases.
Acute renal insufficiency has a very good healing tendency with rapid, professional treatment, but can last up to 6 weeks. This is often followed by a recovery phase in which more urine is produced.
If the acute kidney failure is part of a multiple organ failure (i.e. several organs give up their function in a short time), the prognosis is much less favorable.

Prerenal cause: The kidneys themselves work normally, but the fluid balance of the organism is disturbed. Dehydration, profuse blood loss, very low blood pressure, shock, and severe infectious diseases with sepsis can all lead to prerenal kidney failure. This form of acute kidney failure presents with oliguria (little urine production) and highly concentrated urine. Affected patients should be handled carefully with intravenous fluids.
Intrarenal cause: The kidneys no longer perform their tasks, or only to a limited extent. Medication, poisoning, contrast agents, inflammation of the kidney corpuscles, rhabdomyolysis (rapid breakdown of muscle fibers), malaria and other tropical infectious diseases can lead to intrarenal acute kidney failure.
Postrenal cause: This is where the cause of the kidney failure lies behind the kidney: The urinary tract is narrowed. Causes are e.g. a pelvic tumor, ureteral stones, ureteral tumors, or a prostate that is too large. An ultrasound scan can quickly identify the cause of acute postrenal kidney failure.

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Chronic renal failure

Chronic renal failure describes a gradually worsening, irreversible functional impairment of the kidneys. See also here: kidney values

Course of chronic renal failure as assessed by the GFR

Stages of renal failure

An important reference value for kidney function in kidney failure is the glomerular filtration rate (GFR), which is 95 to 120 milliliters per minute in healthy people. The GFR indicates how much blood volume the kidneys can filter in a certain time unit. It is therefore a parameter for the function and filtration of the kidneys. With the increase in renal insufficiency, the GFR worsens.

Stage 1: Describes a reduced GFR, which is at least 90 ml / min. The filtration capacity of the kidneys is slightly restricted, but the kidney function with regard to the excretion of urinary substances is not impaired. At this stage, those affected often have no symptoms, they may have edema or discolored urine.
Stage 2: Here the GFR is between 60-89ml / min. The kidney function is mildly impaired.
Stage 3: A GFR between 30-59ml / min defines stage 3 renal insufficiency. This results in moderate functional impairment of the kidneys and increased creatinine and urea levels in the blood. The patients show the first symptoms of kidney insufficiency such as high blood pressure, fatigue and poor performance. The risk of cardiovascular diseases is significantly increased at this stage of renal failure.
Stage 4: If the GFR falls to values between 15 and 29 ml per minute, one speaks of stage 4 of renal insufficiency. At this stage, those affected suffer from severe symptoms such as loss of appetite, nausea and vomiting, fatigue, itching, edema, and nerve and bone pain.
Stage 5: With GFR values below 15 ml per minute, stage 5 renal insufficiency is present, also called end-stage renal insufficiency. At this stage, the kidneys are extremely damaged and severely restricted in their function or even functionless. If the kidneys can no longer purify the blood by themselves, kidney replacement procedures (dialysis) are used.

For more information, we recommend our website to: Stages of renal failure

Course of chronic renal failure - assessed by creatinine and urea

The division according to the so-called kidney values, whose concentration in the blood can be determined, is now explained here. The most important of these urinary substances are creatinine and urea, they must be excreted with the urine. When kidney function declines, kidney values rise, which is why they are used as a marker for kidney function.

Also read the article on the topic: Urinary poisoning

Stage 1: The creatinine values at this stage are in the range of 1.2 to 2 mg / dl. The function of the kidneys can be restricted at this stage, but does not have to be, because other metabolic processes in the body can also lead to a slight increase in creatinine. Conversely, a slight renal insufficiency can also be present if the creatinine values are normal: Creatinine inevitably rises only when the kidney function is restricted with a GFR below 60 ml / min.
In stage 1, the patients have few or no symptoms: the urine may be light colored (the kidneys' ability to concentrate less), there is also increased protein in the urine (foamy urine) and slight edema.
Stage 2: Now the creatinine values are between 2 and 6 mg / dl. This stage is known as “compensated retention”. This means that although urinary substances remain in the body, they are still excreted in sufficient quantities.
Stage 3: In stage 3, however, this is no longer the case: Substances that require urine remain in the blood to a large extent, which is referred to as "decompensated retention". The creatinine values are between 6-12mg / dl. The patients have clear symptoms of renal insufficiency: high blood pressure, fatigue, decreased performance, nausea, itching, bone pain, severe edema.
Stage 4: The creatinine levels in stage 4 are above 12mg / dl. Stage 4 describes terminal renal failure with severe kidney function impairment. Rapid dialysis treatment is necessary to eliminate the urinary substances. Dialysis treatment is necessary until a suitable donor kidney for a kidney transplant can be found. If the patients are not treated with dialysis, life-threatening uremia (urine poisoning) with unconsciousness and coma occurs.

You might also be interested in: Stages of renal failure

Therapy of renal failure

Acute renal failure: In the case of acute renal insufficiency, the underlying disease causing the disease is treated first.

In addition, symptomatic therapy of renal insufficiency can be carried out, which is a Balancing of the fluid and electrolyte balance of the patient. Specifically, this means the documentation of the recorded (Drinks, infusions) and the discharged liquid (urine, sweat, diarrhea, Vomit etc.) including daily weighing. In addition, to maintain urine production, special dehydrating agents (Loop diuretics) administered.

The last option for treating renal failure is what is known as a Renal replacement therapy on. In this process, the patient's blood is cleaned of excess water and urinary substances outside the body and then filtered back again (Hemodialysis, hemofiltration, combined methods).

Chronic renal failure: Preventing the progression of the disease and starting treatment early is important in the treatment of chronic kidney failure. At first, this can be tried conservatively: Treatment of the underlying disease, Stopping kidney-damaging drugs, Lowering blood pressure (increased values damage the kidneys), low in protein diet (to reduce kidney blood filtration), increased fluid intake, administration of loop diuretics (Dehydrating agent), Control of electrolytes, lowering of cardiovascular risk factors.

If the effect is insufficient, the chronic form of renal insufficiency as well as the acute one is treated with a kidney replacement procedure. If this therapy option fails, there is still the possibility of one Kidney transplant.

forecast

Acute renal failure: In intensive care patients with acute renal insufficiency, the mortality rate is (mortality ) at 60%. On the one hand, the underlying disease influences the mortality rate; on the other hand, acute kidney failure itself - regardless of the disease causing it - is a prognostically unfavorable factor, as it has a damaging effect on body and organ functions.

Chronic renal failure: The prognosis of the chronic form Dialysis therapy (Kidney replacement procedure) depends on the age of the patient. Overall, the 10-year survival rate is around 55%, but it decreases with increasing age. Became a Organ transplant completed, optimal blood pressure adjustment, treatment of high blood lipids (Hyperlipidemia) and protein loss in urine (Proteinuria), Normal weight and abstinence from nicotine are decisive. The origin of the new organ also plays a role, because with a corpse donation the kidney still functions in 70% of patients after 5 years, with a living donation, however, in up to 90%.

Life expectancy

Basically, the earlier kidney failure is recognized and treated, the better the prognosis and life expectancy. In the case of chronic kidney weakness, cure is usually not possible and the lifespan can be shortened. In particular, the simultaneous occurrence of kidney failure and diabetes mellitus have a negative impact on life expectancy. Consequential damage such as diseases of the cardiovascular system can lead to serious complications. In the case of pronounced renal insufficiency, dialysis procedures and, in the best case, a donor kidney can lead to an improvement in the quality of life and an extension of the life span.

For more information on this topic, please also read: Life expectancy with renal insufficiency

Nutrition in case of renal insufficiency

Patients with renal insufficiency should Eat low in protein, low in phosphate and low in potassium, but high in calcium. In addition, a optimal adjustment of blood sugar levels in diabetic patients.

Low protein diet: Are recommended 0.6-0.8 grams of protein per kg of body weight per day. It is important to pay attention to the biological value of the consumed proteins. The biological value is higher, the more essential amino acids (not produced by the body itself) a dish contains. Potatoes with eggs, beans and eggs, milk and wheat have a high biological value. Dialysis patients must however Eat a diet rich in proteinbecause proteins are lost during dialysis treatment.
Low-phosphate diet: Are optimal 0.8-1g of phosphate per day. There is a lot of phosphate in whole grain bread, nuts, liver and other offal, as well as in many dairy products. Quark, cream cheese, camembert and mozzarella are recommended. Contain many foods Phosphate additives (E 338 to E 341, E 450 a to c, E 540, E 543, E544), these foods should be used in case of renal insufficiency better avoided become.
Low potassium diet: In advanced stages of renal insufficiency, potassium often accumulates in the blood, so affected patients should pay attention to the potassium intake, which is optimal 1.5-2g per day. There is a lot of potassium in: Fruit and vegetable juices, dried fruits, nuts, bananas, apricots, avocado, legumes, green vegetables, tomatoes and mushrooms.
Low salt diet: If patients suffer from high blood pressure and kidney failure, a low-salt diet is recommended.
Drinking amount: Dialysis patients in particular must be careful not to overload their kidneys with too much fluid. The amount you drink results from the Urine production one day plus around 500ml additionally. However, almost all foods also contain water, which must be taken into account when calculating the amount of drink.

Read more about the topic here: Kidney failure diet, potato and egg diet

Summary

Renal failure denotes the loss of function of the Kidneys, being between acute and chronic Kidney failure is distinguished. Acute renal insufficiency develops faster than chronic and, in contrast to the chronic form, is in principle reversible (undo).

Renal insufficiency is diagnosed with the help of the anamnesis, the clinical picture, blood and urine tests (especially the retention values creatinine and urea, glomerular filtration rate) as well as imaging procedures (including Ultrasonic). The clinical picture usually includes changes in urine output, with both an increase (Polyuria) as well as a decrease (Oliguria, anuria) may occur.

In both forms of renal insufficiency, therapy is primarily focused on Treatment of the underlying disease leading to loss of function, there is also a conservative therapy with monitoring of the fluid balance and the administration of special dehydrating agents (Loop diuretics). In the case of inadequate success, a. In both acute and chronic renal insufficiency Kidney replacement procedure be initiated, with extracorporeal (= outside the body) devices the Task of filtering blood take over.
The last resort to treat chronic kidney failure is to transplant a new organ.