Renal Disease Meaning

At the beginning, chronic kidney weakness often manifests itself only with minor symptoms or even runs completely asymptomatic. Often, the kidney problems are masked by the symptoms of the underlying disease, e.g., by the symptoms of diabetes or vasculitis. Early symptoms of kidney disease may include:

  • Increased excretion of low-colored, light-colored urine.
  • Increased blood pressure
  • Water retention (edema) in the legs, around the eyes, or all over the body
  • Red urine


A gradual progression with little or no symptoms is characteristic of chronic kidney failure. A first-occurring high blood pressure of over 140/90 mmHg or increasingly difficult to control high blood pressure may be an early sign of disease. Many patients often produce pale, low-concentration urine and store water in the skin and subcutaneous tissue (edema). Foaming urine during urination can be an indication of proteins in the urine. A healthy kidney excretes no more than 200 milligrams of protein per day, including no more than 30 milligrams of the blood protein albumin. Higher values are referred to as microalbuminuria, and 300 milligrams or more of albumin per day as macroalbuminuria or proteinuria. Some patients also excrete blood in their urine. If this occurs in larger quantities, the urine is red in color (macrohematuria). In most cases, however, there is so little blood in the urine that it is not visible to the naked eye and can only be detected by test strips (microhematuria). With progressive loss of function, the kidneys can no longer fulfill their tasks. Disturbances of water balance, acid-base balance, electrolyte balance and other organ systems occur. In addition, the body is more susceptible to infections. Since the kidneys no longer produce sufficient amounts of the blood-forming hormone erythropoietin (Epo), the number of red blood cells decreases. Such anemia leads to fatigue, weakness, difficulty concentrating and decreasing physical resilience. A noticeable pallor of the skin is a possible further clinical indication. In addition, patients often suffer from nausea, vomiting or diarrhea shortly before starting dialysis. Other symptoms may include memory problems, itching and burning in the legs, and muscle and bone pain. In the advanced stage of chronic kidney failure, almost all organ systems are damaged by the kidneys’ lack of detoxification function (uremic syndrome). Pathological changes are found in the cardiovascular system, the hematopoietic system, the gastrointestinal tract, the peripheral and central nervous system, the skin, the endocrine system and the bones. Typical symptoms of end-stage renal disease (terminal renal failure) are:

  • Hypertension that can no longer be controlled
  • Decrease in the amount of urine
  • Water retention (edema)
  • Shortness of breath
  • Nausea, vomiting, loss of appetite
  • Irregular heartbeat
  • drowsiness, drowsiness
  • Convulsions, coma

Staging based on GFR

Chronic kidney failure is classified into five stages using the so-called glomerular filtration rate (GFR). GFR is a laboratory value that is 90-130 milliliters per minute in normally functioning kidneys. This means that a healthy kidney cleans at least 90 milliliters of blood per minute of freely filterable substances and excretes them in the urine.

Stage I: GFR greater than 89 milliliters/minute (with normal kidney function).

In this stage, patients often have no symptoms. The blood values for creatinine are still normal, only protein excretion via the urine may be increased or there may be other indications, e.g. on ultrasound, of kidney disease. If possible causes are identified at this stage, a worsening of the disease can very often still be prevented.

Stage II: GFR between 60-89 milliliters/minute (with mild functional impairment)

Even at this stage, kidney weakness is often not yet detectable by blood tests. The kidneys appear to continue to function adequately, but more detailed examinations reveal kidney disease, e.g., with measurement of urine protein or with ultrasound. In addition, more precise measurements, e.g. creatinine clearance, can detect incipient kidney weakness.

Stage III: GFR between 30-59 milliliters/minute

Kidney damage has now progressed to the point where elevated creatinine and urea levels are also measured in the blood. Those affected suffer from high blood pressure, reduced performance and more rapid fatigue. In stage III, the risk of cardiovascular disease also increases significantly. The symptoms are open to various interpretations and do not necessarily indicate kidney weakness. Drugs that are normally excreted by the kidneys must now be reduced in dose so that they do not cause side effects.

Stage IV: GFR between 15-29 milliliters/minute

At this stage, so many kidney cells are already defective that the inadequate excretion of toxins affects the entire organism. The symptoms therefore increase: loss of appetite, fatigue, vomiting, nausea, nerve pain, itching and bone pain. Because the body excretes fewer salts and water, edema also occurs.

Stage V: GFR below 15 milliliters/minute

If kidney function is very severely reduced or if the kidneys fail completely, this is also referred to as terminal renal failure. At this stage, the blood must be regularly cleansed of toxins by blood washing (dialysis), otherwise the body becomes poisoned. Despite regular blood washing, terminal renal failure can still cause a yellowish discoloration of the skin and skin itching. Both are due to the storage of substances in the skin that should actually be excreted through the urine. Status: 23.08.2021 12:24 hrs More and more people are suffering from kidney weakness. The tricky thing is that the disease does not cause any noticeable symptoms at the beginning. Yet early treatment is important to save kidney tissue. The kidneys clean the blood, regulate blood pressure, salt and water balance and produce important hormones. They do their work unnoticed, even when they are getting worse. More and more people are developing progressive kidney weakness without realizing it. In Europe, ten percent of adults already have chronic kidney disease and in many cases eventually become dependent on artificial blood washing (dialysis) or a kidney transplant.

Risk factors for kidney weakness

High blood pressure, diabetes and arteriosclerosis in particular damage the very fine vessels of the kidneys in the long term. In addition, obesity puts a strain on them. In people with severe overweight (obesity), several risk factors for kidney failure often come together. For example, the fatty tissue in the abdominal cavity produces inflammatory hormones that further endanger the kidneys. Other serious consequences include cardiovascular disease and reduced life expectancy.

Obese children are more likely to develop kidney weakness later on

More and more children and adolescents are now severely overweight and suffer from type 2 diabetes. They run the risk of being dependent on regular machine blood washing at the age of 30 to 45 – for the rest of their lives.

Kidney weakness due to smoking or medication

Cigarettes, an unhealthy diet with a lot of pork, and painkillers such as ibuprofen or diclofenac taken over a long period of time can also cause massive damage to the kidneys.

Kidney damage in autoimmune diseases

Autoimmune diseases can also attack the kidney. In glomerulonephritis, the autoimmune event turns exclusively against the kidneys. In some systemic autoimmune diseases, the kidney is affected – in particular vasculitides, i.e. inflammation of the blood vessels, and collagenoses, which attack the connective tissue. The most common diseases with kidney involvement include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and systemic lupus erythematosus (SLE).

Symptoms of kidney weakness

As we age, kidneys naturally become weaker. Symptoms that may indicate kidney problems include:

  • high blood pressure
  • stabbing headache
  • water in the legs
  • skin that tightens
  • foam on the urine

In the final stage of renal insufficiency, the following symptoms may occur:

  • hypertension that can no longer be controlled
  • decrease in the amount of urine
  • water retention (edema)
  • Shortness of breath
  • Nausea
  • Vomiting
  • loss of appetite
  • irregular heartbeat
  • Drowsiness
  • Drowsiness
  • Convulsions
  • Coma

Examination for kidney weakness

Declining kidney function can be detected with blood and urine tests:

  • A first indication is provided by the creatinine value in the blood. Creatinine is a breakdown product of the acid creatine, which supplies the muscles with energy. It accumulates in the blood when the kidneys are not working properly. However, the creatinine level only increases when kidney function is already reduced by more than 50 percent.
  • Also an increased protein excretion in the urine also indicates kidney damage.
  • More sensitive are the more complex laboratory tests for the protein cystatin C and the freely circulating urokinase receptor suPARwhich indicate a kidney problem long before the first symptoms appear. Caution: In older people, an excessively high creatinine level can become so bad within just a few months that dialysis becomes necessary. Therefore, the kidneys should be taken just as seriously as the heart, experts warn.

Treating kidney weakness

In most cases, kidney damage cannot be reversed. If kidney damage is detected in time, the progression of the disease can often be slowed down with medication and the right diet. Anyone suffering from diabetes, obesity and high blood pressure should have their kidney values checked regularly and, if possible, change course in good time: plenty of exercise and a kidney-healthy diet can at least help to prevent the disease from getting worse, thereby delaying serious kidney damage.

Kidney failure: dialysis or transplantation

If organ function has already fallen to less than ten percent, artificial blood washing (dialysis) is usually the only option. The only alternative is a kidney transplant, but donor organs are in short supply.

Living kidney donation and cross-over living donation

A special way to get a donor kidney is through living kidney donation. Fortunately, people can get by with just one kidney, otherwise living donations would not even be possible. In order to avoid organ trafficking and the associated criminality, the German Transplantation Act (TPG) lays down strict requirements for living kidney donation: for example, living kidney donation in Germany is only permitted between family members and people who have a special personal relationship (first- or second-degree relatives, spouses, registered partners, fiancées or close friends). However, if the medical conditions of a donor-recipient pair are not correct (tissue or blood group incompatibility), in very rare cases a “cross-over living donation” (cross-over transplantation) can be performed between two donor-recipient pairs. For this purpose, another couple is sought in whom the immunological prerequisites for a reciprocal donation are also not given. The two couples must meet in person and give a credible assurance to a living donor committee that they are willing to donate a kidney to the other recipient. In some German states, however, cross-over transplants are not permitted. In Germany, it is currently still difficult to find matching couples because there is no central database for pre-selection. Since a great deal of medical data has to be matched, appropriate computer programs are also necessary. Abroad, these have already taken over the planning of crossover donations decades ago.

How the kidney filters the blood

In the kidneys, about three million renal corpuscles filter harmful substances from the blood. In the kidney corpuscles, so-called phalanx cells form a special grid-like structure: healthy phalanx cells allow small molecules such as water and nitrogen compounds to pass through, which are discharged with the urine. Large molecules such as blood cells and protein do not pass through and remain in the blood. In a diseased kidney, the lattice structure of the phalanx cells is much more permeable: the blood loses large molecules, for example important proteins and vitamins. Further information This topic in the program:

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Definition of chronic kidney disease

Chronic kidney disease is defined by two criteria:

  • Kidney damage for longer than 3 months, diagnosed by non-normal protein/protein levels or by finding abnormal changes on imaging (ultrasound or CT or MRI).
  • A decrease in renal function to below 60%, regardless of whether renal impairment is present.


Kidney disease has a wide range of effects on life and quality of life. Often, the disease develops insidiously and is discovered late. Chronic kidney disease patients often develop secondary diseases. In Germany, there are currently an estimated 10 million chronic kidney disease patients in all stages. The incidence of chronic kidney disease, especially diabetic and vascular nephropathies, has risen sharply in recent times. Patients with impaired renal function are at increased risk of developing end-stage renal failure, and more importantly, cardiovascular complications and death.

Too late detection

In most cases, kidney disease is detected far too late, since the kidney is a “silent organ” and impairment of organ function does not become immediately apparent through pain or other noticeable symptoms. This has fatal consequences: If the nephrologist only detects the kidney disease at the stage of terminal renal failure, the damage can usually no longer be repaired. The stage of dialysis requirement can be significantly delayed by intensive general measures such as particularly sustained blood pressure normalization. However, the reality is different: Many patients are presented to the kidney specialist too late. Dialysis can then no longer be delayed. According to estimates by the Society of Nephrology, kidney failure need not have developed in 15 % of dialysis patients, and in 30 to 40 % of patients, early detection could have postponed the need for dialysis by at least years. Improving the prognosis of these patients primarily requires timely diagnosis based on reliable and simple determination of kidney function.

Causes and risk factors

There are many risks and causes of kidney disease:

  • Age 60 and older (kidney function declines with age).
  • Skin color
  • Diabetes mellitus
  • The long-term effects of diabetes can destroy the fine blood vessels of the kidney corpuscles through arteriosclerosis
  • High blood pressure (about 10 million people in Germany have high blood pressure)
  • Immune diseases
  • Congenital malformations (e.g. cystic kidneys) can remain undetected for a long time and lead to gradual loss of kidney function
  • Urine outflow disorders
  • Long-lasting or repeated kidney infections
  • Medications (e.g. painkillers) and environmental toxins can affect the kidney in the long term
  • Drugs
  • and others.

Chronic kidney failure can develop due to a variety of causes. The most important goal for chronic kidney disease patients is to delay the development of the disease as long as possible, to address the specific characteristics of the disease in dialysis patients and transplant recipients, and to provide timely prevention.

Diagnosis of chronic kidney disease

For the detection of chronic kidney disease are used:

  • A urine test (measuring the concentration of a protein, e.g. albumin).
  • A blood test (determination of a blood value, creatinine)


It is recommended to consult a nephrologist from stage 3. Similarly, timely treatment of all concomitant diseases is required.

Life on dialysis

Life on dialysis is a life with severe limitations in quality of life and with significantly reduced chances of survival. A transplant improves the quality of life considerably.

Further information

For further information, please contact your nephrologist. There are guidelines for nephrologists that can be accessed at NKF KDOQI. In chronic kidney disease, the decline in kidney function progresses slowly over months to years, and the kidney’s ability to filter metabolic waste products from the blood gradually diminishes.

  • The most common causes of this are diabetes and high blood pressure.
  • Blood acidity is increased, anemia develops, nerves are damaged, bone tissue is broken down, and the risk of developing atherosclerosis increases.
  • Symptoms such as urination at night, fatigue, nausea, itching, muscle twitching and cramps, loss of appetite, confusion, breathing problems, and swelling of the body (most commonly the legs) may occur.
  • Diagnosis is made by blood and urine tests.
  • The goal of treatment is decreased dietary intake of fluids, sodium and potassium, drug treatment of other conditions (such as diabetes, hypertension, anemia and electrolyte imbalance) and, if necessary, dialysis or kidney transplantation.

Both disorders damage the small blood vessels of the kidney. Other causes of chronic kidney disease include blocked urinary tract Urinary tract obstruction Urinary tract obstruction prevents urine from flowing through the normal pathway (the urinary tract), which includes the kidneys, ureter, bladder, and urethra. The obstruction… Learn more , certain kidney abnormalities (such as polycystic kidney disease Polycystic kidney disease (PKD) Polycystic kidney disease is an inherited disorder that causes fluid-filled cavities (cysts) to form in both kidneys. The kidneys become larger than normal, have… Learn More and Glomerulonephritis Glomerulonephritis is a disease of the glomeruli (capillary tangles in the kidneys through whose small pores blood is filtered). It is characterized by tissue swelling (edema), hypertension,… Learn More ) as well as autoimmune diseases (such as systemic lupus erythematosus Systemic lupus erythematosus (SLE) Systemic lupus erythematosus is a chronic inflammatory autoimmune disease of connective tissue that affects joints, kidneys, skin, mucous membranes, and the walls of blood vessels…. Learn more ), in which antibodies damage the tiny blood vessels (glomeruli) and tubules of the kidneys. Chronic kidney disease can lead to many problems throughout the body:

  • With mild to moderate loss of kidney function, the kidneys cannot absorb water from the urine, which is needed to decrease the volume and increase the concentration of urine.
  • High concentrations of metabolic waste products in the blood can damage nerve cells in the brain, trunk, arms and legs. An increase in uric acid concentration is possible, which can lead to gout.
  • The diseased kidneys produce hormones that can increase blood pressure. In addition, the damaged kidneys cannot excrete the excess salt and water. Salt and water retention can contribute to high blood pressure and heart failure.
  • In addition, the formation and maintenance of bone tissue may be impaired (renal osteodystrophy) if certain factors associated with chronic kidney disease persist over a long period of time. These include high levels of parathyroid hormone, low levels of calcitriol (calcitriol is the active form of vitamin D) and high levels of phosphate in the blood, and impaired calcium absorption. Renal osteodystrophy can lead to bone pain and an increased risk of fractures.

Symptoms usually develop very slowly. If renal insufficiency progresses and metabolic waste products build up in the blood, symptoms also increase. Mild to moderate loss of kidney function may cause only mild symptoms. may only lead to mild symptoms, such as frequent urination at night (nocturia). When the kidneys cannot reabsorb water from the urine to reduce its volume and concentrate it (which usually occurs at night), nocturia develops. As kidney failure progresses and metabolic waste products accumulate in the blood, the more the affected person feels exhausted, becomes weak and mentally sluggish. This can result in loss of appetite and shortness of breath. Anemia also leads to fatigue and a general feeling of weakness. A severe loss of kidney function leads to increased accumulation of metabolic waste products in the blood. Damage to the kidneys can cause muscle twitching, muscle weakness, cramps and pain. In the limbs, the affected person may feel a burning and stinging sensation and lose sensation in certain parts of the body. In some circumstances, restless leg syndrome develops. Encephalopathy, damage to the brain that can lead to confusion, lethargy and seizures, may develop. Heart failure may cause shortness of breath. Swelling of the body may occur, especially in the legs. Pericarditis may cause chest pain and low blood pressure. People with advanced chronic kidney disease usually develop gastrointestinal ulcers and bleeding. The skin may turn yellow-brown, and sometimes the urea concentration is so high that the substance crystallizes out of sweat and powders the skin white (uremic frost). Some patients with chronic kidney disease have very unpleasant itching all over the body. There may also be bad breath.

  • Blood and urine tests
  • Ultrasound
  • Sometimes biopsy

It is important to perform blood and urine tests. In this way, the decline in kidney function can be confirmed. When a certain degree of chronic kidney disease is reached, the levels of chemicals in the blood are usually abnormal.

  • Urea and creatinine levels – metabolic waste products that are normally filtered out by the kidneys – are elevated.
  • The blood reacts moderately acidic (acidosis).
  • Blood potassium levels are often unremarkable or only slightly elevated, but can also rise to dangerously high levels.
  • Calcium and calcitriol levels in the blood decrease.
  • In contrast, phosphate and parathyroid hormone levels rise.
  • Hemoglobin levels are usually lower, i.e., there is anemia.

Blood potassium levels can rise dangerously if renal insufficiency progresses or the patient ingests large amounts of potassium, or takes a drug that prevents potassium excretion by the kidneys. A urinalysis can reveal many disorders, such as protein in the urine and altered cells. An ultrasound is often done to rule out a blockage and to check the size of the kidneys. Small, scarred kidneys often indicate a chronic form of kidney failure. As kidney failure progresses, it becomes increasingly difficult to find an exact cause. A tissue sample (kidney biopsy) may be the most informative. However, it is not appropriate if ultrasound shows that the kidneys are small and scarred. If chronic kidney disease is caused by a condition that can be corrected (e.g., blocked urinary tract) and the condition has not been present for too long, kidney function may improve if the underlying condition is successfully treated. Otherwise, kidney function often worsens over time. The rate of decline in kidney function depends to some extent on the disease underlying the chronic kidney disease and the extent to which it can be controlled. Poorly treated diabetes or hypertension will lead to a more rapid reduction in kidney function. Chronic kidney disease leads to death if left untreated.

  • Treatment of the disorders that worsen kidney function
  • Nutritional measures and medications

The goal of treatment is to slow the decline in kidney function. Circumstances that can cause or worsen chronic kidney disease and affect health should be corrected quickly, for example

  • Infections
  • Use of certain medications

Good control of blood sugar and lowering high blood pressure slow the decline in kidney function in diabetics. So-called ACE (angiotensin-converting enzyme) inhibitors and also angiotensin II receptor blockers (ARBs), which lower blood pressure, can halt the deterioration of kidney function in some people with chronic kidney disease. Drugs called sodium/glucose cotransporter 2 protein inhibitors (SGLT-2 inhibitors) can also slow the deterioration of renal function, but should be avoided in people with type 1 diabetes mellitus. Drugs that are excreted by the kidneys are not prescribed, or doses of these drugs are largely reduced. Many other medications may need to be avoided completely. For example, ACE inhibitors, ARBs, and certain diuretics (such as spironolactone, amiloride, and triamterene) may need to be discontinued in people with severe chronic kidney disease and high potassium levels, as these drugs can increase potassium concentrations. Urinary tract obstructions are removed or improved. Bacterial infections are treated with antibiotics. Dietary measures should be taken and medications may be prescribed to slow the progression of chronic kidney disease. The deterioration of kidney function can be delayed somewhat by limiting the amount of protein consumed daily. In this case, the affected person must consume sufficient carbohydrates to compensate for the reduced protein intake. If protein intake is significantly restricted, this should be monitored by a dietitian to ensure the intake of adequate amounts of amino acids. Blood triglyceride and cholesterol levels can be controlled to some extent by a lower-fat diet. The use of medications such as statins, ezetimibe, or both may be required to lower triglyceride and cholesterol levels. Care may need to be taken to reduce fluid intake to prevent sodium levels from becoming too low. Foods high in potassium, such as dates and bananas, should be consumed only in moderation; table salt substitutes, which usually consist of a potassium salt, should be avoided completely. (For more information, see the National Kidney Foundation publication Potassium and Your CKD Diet.) Increased phosphate levels in the blood can lead to calcium and phosphate deposits in tissues, including blood vessels. Phosphate levels can be limited by limiting the amount of high phosphate foods in the diet; these include dairy products, liver, vegetables, nuts and most soft drinks. Taking medications such as calcium carbonate, calcium acetate, sevelamer, lanthanum, and ferric citrate, which lower blood phosphate levels, can also help. Calcium citrate should be avoided completely. Calcium citrate is found in many calcium supplements and is used as an additive (sometimes listed as E333) in many products. Vitamin D and similar supplements are often taken to lower high parathyroid hormone levels. The anemia caused by the chronic kidney disease anemia can be treated with

  • Medications such as erythropoietin or darbepoetin
  • Blood transfusions

Blood transfusions are only considered if the anemia is threatening, causing symptoms, or not responding to erythropoietin or darbepoetin. A hypertension is treated with antihypertensives to prevent further impairment of heart and kidney function. Dehydrating agents (diuretics) may be used even to reduce the symptoms of heart failure when the kidneys are working poorly. However, dialysis may be necessary to eliminate the excess fluid. The following are some English language resources that may be useful. Please note that the MANUAL is not responsible for the content of these resources.

  • National Kidney Foundation (NKF): The NKF provides information on kidney disease and kidney transplantation, need-based financial assistance for medical expenses, webinars for medical professionals, and advocacy opportunities.

NOTICE: This is the issue for patients. PHYSICIANS: VIEW THE ISSUE FOR MEDICAL PROFESSIONALS VIEW THE ISSUE FOR MEDICAL PROFESSIONALS. Copyright © 2022 Merck & Co, Inc, Rahway, NJ, USA and its affiliates. All rights reserved. Renal Disease Meaning.

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