Brief overview
- Renal insufficiency – Definition: In renal insufficiency (kidney weakness, kidney failure), the kidneys have limited or no ability to excrete urinary substances – i.e. substances (such as urea) that must be continuously excreted in the urine because otherwise there is a risk of damage to health.
- Disease forms: acute renal failure (sudden onset, potentially reversible) and chronic renal failure (gradual onset, usually progressive, not reversible, but can be slowed if necessary).
- Causes: In sudden renal failure, e.g., accidents, burns, inflammation, infection, heart failure, tumors, kidney stones, medications. In the case of chronic kidney weakness, e.g. diabetes, high blood pressure, kidney cysts, inflammations, medications.
- Treatment: Depending on the cause and severity of renal insufficiency. Treatment of the cause and existing risk factors (such as high blood pressure), regulation of fluid, acid-base and electrolyte balance, avoidance of drugs that damage the kidneys, dialysis or kidney transplantation if necessary. In addition, dietary recommendations.
What is renal insufficiency?
In renal insufficiency (kidney weakness, kidney failure), the kidneys can no longer perform their main function, or can do so only to a limited extent. This consists of continuously filtering and purifying the blood – that is, filtering out excess water, minerals and metabolic products and excreting them as urine.
What happens in kidney failure?
When the kidneys can no longer filter the blood (sufficiently), urinary substances accumulate in the body. These are end products of metabolism that must be excreted with the urine, such as urea, uric acid and creatinine.
In addition, water and minerals also accumulate in the body during renal insufficiency. Among other things, this can cause tissue swelling (edema) and cardiac arrhythmias (due to too much potassium). As a further consequence, metabolic acidosis (metabolically “acidic” blood) can develop in renal insufficiency.
Renal insufficiency – acute or chronic
Physicians speak of acute renal insufficiency when kidney function declines acutely, i.e. within a short period of time. This loss of function is potentially reversible. You can read more about this in the article Acute renal failure.
In chronic renal failure, kidney function declines gradually and permanently. You can find more information about this form of kidney damage in the article Chronic renal failure.
Is kidney failure curable?
If “kidney failure” correctly refers to the end stage of chronic renal insufficiency, the answer is no (in terms of the diseased kidneys). The kidney damage here is so extensive that sufferers are dependent on dialysis (“blood washing”) to survive – or on a new kidney (kidney transplant).
Even in earlier stages, chronic renal failure is not curable in the sense that the already destroyed kidney tissue regains its functional capacity. With early and proper treatment, however, the disease does not even progress to the final stage (or at least only very slowly).
Acute renal failure, on the other hand, can heal: If it is treated quickly, kidney function usually recovers completely. However, a small proportion of patients are left with chronic kidney failure. Without treatment, kidney failure is usually fatal.
A blanket answer to this question is not possible. Basically:
Dialysis can be life-saving in cases of severe kidney damage. However, the life expectancy of chronic dialysis patients is significantly reduced (compared to the normal population of the same age).
The situation is particularly critical if concomitant diseases such as diabetes or cardiac insufficiency are also present. Other factors, such as the patient’s age, also influence the extent to which life expectancy is shortened in the case of kidney failure.
The prognosis looks better when patients with severe kidney disease receive a donor kidney: They have a significantly higher life expectancy after kidney transplantation than dialysis patients.
Read more about the life expectancy of people with chronic kidney failure here.
How does kidney failure occur?
In old and frail people in particular, acute kidney failure is often due to the fact that they drink far too little, so that the body dries out (dehydration). Certain medications, infections, non-infectious kidney inflammation, tumors or heart failure can also trigger sudden kidney failure.
You can learn more about the causes of acute kidney failure here.
Chronic kidney failure is very often caused by diabetes. The persistently elevated blood glucose levels damage the renal corpuscles (glomeruli), i.e. the filtering units of the kidneys. This form of kidney damage is called “diabetic nephropathy”.
Long-standing high blood pressure also often chronically damages the kidneys. Other possible causes include kidney inflammation and cystic kidney disease (usually congenital formation of numerous fluid-filled cavities (cysts) in the kidneys).
Renal insufficiency: symptoms
Acute renal failure often presents with only nonspecific symptoms, such as rapid fatigability. The most noticeable symptom may also be a decrease in the amount of urine. However, this does not always happen. Some affected individuals even excrete excessive amounts of urine (polyuria).
Chronic kidney weakness initially shows no symptoms. Only as kidney damage progresses do signs of the disease gradually appear, for example weakness, itching, dirty-yellow skin coloration (café-au-lait skin color) and urine-like odor of exhaled air, skin and sweat (uremic fetor).
If the kidneys excrete too little water, it usually accumulates in the tissues. The result is, for example, water retention (edema) in the legs. However, “overhydration” can also affect the lungs (pulmonary edema).
Read more about the signs of impaired kidney function in the article Kidney failure – symptoms.
Renal insufficiency: Diagnosis
The diagnosis begins with a detailed discussion between the doctor and patient to obtain a medical history. Among other things, the doctor asks what complaints the patient has and how long they have existed. He also inquires about underlying diseases (such as high blood pressure) and medications that the patient is taking.
The medical history interview is followed by a physical examination and blood and urine tests. Blood values relevant to renal insufficiency include creatinine, urea and creatinine clearance. These kidney values give the physician an indication of how much the kidney function is impaired.
The detection of an increased amount of protein in the urine (proteinuria) is also informative. It often signals renal insufficiency, but can also have other causes.
You can find out more about examinations and diagnosis of acute renal failure here. If you would like to know more about the evaluation of chronic kidney failure, please read on here.
Renal failure: stages
Acute renal failure can be divided into four stages in the course of the disease, among others: It begins with the damage phase (initial phase), which lasts only hours to days, and ends with the recovery phase. During the latter, kidney function more or less recovers, which can take up to two years. In addition, acute kidney failure is divided into three stages, depending on the extent of kidney values and urine output.
You can find out more about the stages and progression phases of acute kidney failure here.
You can read more about the different degrees of severity of chronic kidney failure in the article Kidney failure – stages.
Renal insufficiency: Treatment
Renal insufficiency therapy depends on the cause and severity of the condition.
In any form of renal insufficiency, doctors monitor and regulate the acid-base and electrolyte balance (electrolytes = blood salts). They may prescribe medication for this purpose. So-called diuretics (“water tablets”) are sometimes necessary so that those affected can still urinate sufficiently and eliminate “toxins”.
It is also important to avoid drugs that damage the kidneys in cases of renal insufficiency or to use them only with caution and in reduced doses. For example, the well-known painkiller and antipyretic ibuprofen must not be taken in severe renal insufficiency.
It is best to take medications only after consulting your doctor.
You can read more about the treatment of acute renal failure here. You can read about how chronic kidney failure is treated here.
Renal insufficiency: Nutrition
Patients with renal insufficiency can also do something themselves to relieve the strain on their kidneys and improve their general condition. For example, it is important to keep an eye on your own protein and calorie intake. Impaired kidney function can lead to increased protein breakdown and fat metabolism disorders.
People with chronic renal insufficiency should consume foods that contain a lot of phosphate, either naturally or as an additive, in moderation. These include nuts, offal, wholemeal bread, milk, processed cheese and some types of sausage.
Special recommendations also apply to patients with kidney failure who are receiving dialysis.
You can read more about this topic in the article Nutrition in renal failure.
