Renal failure leads to impaired kidney function. As a result, the concentration of urinary substances such as creatinine and urea (substances that must be excreted through the kidneys) increases in the blood. Regulation of water, electrolyte and acid-base balance is disturbed. Because the kidneys also produce hormones or activate vitamins, blood formation disorders and changes in bone metabolism can occur.
The kidneys can be damaged by inflammatory processes, vascular calcification and various other diseases (high blood pressure, diabetes, genetic factors).
In acute renal failure, the kidneys lose their ability to function relatively suddenly – usually within a few hours or days. The disease is life-threatening if left untreated. The extent to which kidney function subsequently improves depends largely on the precipitating cause.
Causes of Kidney Failure
Acute renal failure can be triggered by many factors. These are divided into three groups.
The cause is “before” the kidneys (prerenal renal failure):
The kidneys are no longer supplied with enough blood. Possible triggers for this most common form of acute kidney failure include:
- Heart disease (e.g. heart failure, heart attack),
- Pulmonary embolism
- Major bleeding (e.g. as part of an injury or surgery),
- Burns,
- Severe inflammation with circulatory failure.
The cause lies in the kidneys (intrarenal renal failure):
Pathological changes occur in the renal vessels, kidney filter bodies or kidney connective tissue. Possible triggers include:
- Inflammation (e.g. glomerulonephritis, but also infections),
- Medicines,
- Poisoning,
- Immune system disorders.
The cause is “behind” the kidneys (postrenal renal failure):
A blockage in the ureter or bladder causes a backup of urine. Possible causes are:
- Urinary stones
- Prostate enlargement
- Tumors.
Causes of chronic renal failure
The causes of chronic kidney failure are varied. The most important ones include:
- Diabetic nephropathy – kidney damage caused by diabetes mellitus (sugar diabetes)
- Kidney inflammation: chronic glomerulonephritis or interstitial nephritis and recurrent inflammation of the renal pelvis (chronic recurrent pyelonephritis)
- Diseases of the blood vessels of the kidney, “calcification” of the renal arteries (atherosclerosis)
- Cystic kidneys
In about 10 percent of cases, the cause is unknown. All diseases that can lead to kidney failure should be treated as early and well as possible. Optimal treatment for diabetes mellitus and high blood pressure is particularly important.
Symptoms of Kidney Failure
Acute kidney failure usually causes symptoms within a short period of time:
- Urine production is often reduced and may even stop completely. But sometimes the kidneys continue to pass urine.
- The substances needed in the urine remain in the body – as indicated by elevated levels of creatinine and urea in the blood.
- There are signs that the body is taking in too much fluid, such as fluid in the lungs (pulmonary edema) or in the legs.
- Disturbances in the salt balance (electrolyte disturbances), e.g. high levels of potassium in the blood, are possible. Hyperacidity (acidosis) comes into play. Both of these can be life-threatening.
With adequate treatment, the kidneys can gradually recover, allowing urine production to resume and other functions (such as electrolyte and acid-base regulation) to return to normal. It usually takes weeks to months for kidney function to fully recover.
Symptoms of chronic renal failure
Chronic kidney failure (CKD) develops slowly. It may initially go unnoticed or cause non-specific symptoms such as exhaustion, fatigue or loss of appetite. Blood pressure may rise. Fluid retention, for example in the legs or lungs, is sometimes noticeable. The latter can cause shortness of breath. The kidneys may no longer concentrate the urine as they should. The amount of urine may then initially increase – which does not cause those affected to think of kidney weakness. The urine is then usually light in color and not very concentrated.
Doctors divide CKD into stages according to the functional state of the kidneys. To do this, they use various parameters such as protein excretion in the urine or blood values with the so-called glomerular filtration rate (GFR) estimated from them. Describes the amount of blood freed from creatinine by the kidneys per minute. GFR is given in milliliters per minute (ml/min). A normal GFR is more than 90 ml/min.
Untreated kidney failure can have numerous effects on the whole organism. Because the kidneys perform important tasks, including hormone production. Possible consequences of kidney failure are: anemia, high blood pressure, bone problems, sensory disorders due to nerve damage (polyneuropathy), disorders of the genital organs without menstruation (amenorrhea) or impotence, clotting disorders with bruising. Headaches or itching also occur over time.
Kidney Failure Treatment Methods
Treatment options range from treating the causes to drug therapy and kidney replacement therapy through dialysis or kidney transplantation.
Treatment of acute renal failure
If fluid deficiency caused acute renal failure, this needs to be compensated for. A very low blood pressure is raised by appropriate measures.
If a medicine has caused acute renal failure (ANF), the medicine should be taken after consulting a doctor or stopped immediately. For example, certain antibiotics, painkillers and X-ray contrast agents can trigger an AKI.
If there is an obstruction in the urine flow (e.g. stones, enlarged prostate), this should be removed.
In rare cases, with severe immunologically-induced inflammation of the glomeruli (“rapid progressive glomerulonephritis”), with rapid loss of function of the kidneys, the doctor treats with special medications ( immunosuppressants). They stop the destruction of kidney corpuscles.
Once the triggers of acute kidney failure have been eliminated as far as possible, doctors can try to restore kidney function: They may prescribe drugs that “boost” elimination function again. First and foremost are so-called loop diuretics. However, high doses should be avoided. If restoration of kidney function is not possible, the kidney replacement procedure is used until kidney function is restored.
Treatment of chronic renal failure
The focus is on treating the underlying disease that leads to chronic renal failure (CRF):
- If you have diabetes (diabetes mellitus), optimal blood sugar control through proper nutrition and medication is particularly important.
- In the case of high blood pressure, the blood pressure needs to be brought to the best possible values – plenty of exercise, a healthy diet and medication.
- Some types of kidney inflammation (glomerulonephritis) can be treated with drugs (called immunosuppressants) that slow down the destruction of the kidneys.
- Antibiotics are usually used for kidney infections.
High blood pressure, present in many diseases leading to CKD, is preferably treated with ACE inhibitors or angiotensin II receptor antagonists. In addition, all other blood pressure-lowering drugs (diuretics, beta-blockers, calcium antagonists) can also be used for optimal blood pressure regulation.
Close-knit follow-up controls
Chronic kidney weakness worsens more or less rapidly, regardless of the underlying condition. The best possible treatment helps to positively influence the course of the disease.
The doctor will closely monitor the patient’s health, especially blood pressure readings. They advise on the most appropriate individual diet and the amount of water to drink. The aim is to have as balanced a fluid, salt and acid-base balance as possible. It is often helpful for the patient to check their weight on a daily basis. Strong fluctuations caused by fluid transitions are quickly noticeable. Blood values measured at this time also provide important clues.
