Acute kidney failure
Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.
More about the experts All content is checked by medical journalists.
Medical professionals describe a sudden drop in kidney function as acute kidney failure. Substances that should actually be excreted with the urine accumulate in the blood, which leads to symptoms of poisoning (urinary poisoning). Acute kidney failure is often the result of surgery or accidents. If it is not treated quickly, there is a mortal danger.
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. N17
Acute kidney failure: description
The term "acute kidney failure" (acute renal insufficiency or kidney weakness) stands for the sudden, sharp decline in the detoxification function of the kidneys within hours to days. The so-called glomerular filtration rate (GFR) decreases acutely. And this also reduces the volume of fluid that is filtered in the kidney per unit of time. Affected are the so-called glomeruli - clusters of vessels in the kidney that act as tiny filters.
Acute kidney failure causes substances to accumulate in the blood that should actually be excreted in the urine. These so-called urinary substances include urea and creatinine. Their accumulation in the body leads to gradual urinary poisoning. Doctors speak of uremia.
Acute kidney failure: four stages
In most cases, acute kidney failure has four stages:
- Damage phase (initial phase): It lasts from a few hours to days.
- Oligo- or anuric phase: In this stage, the urine excretion decreases significantly until little (oligouria) or practically no urine (anuria) leaves the body. This phase generally lasts ten days.
- Recovery phase: When the kidneys recover, they produce more and more urine (up to five liters and more per day). This phase lasts about three weeks.
- Recovery phase: Now the kidney cells become more or less functional again, although a complete healing of the disease is not always possible. This final stage can take up to two years.
Acute kidney failure: Fatal
About 50 out of 1 million people develop acute kidney failure each year. It occurs more frequently in intensive care patients. Acute kidney failure occurs in up to 25 percent of them. It has to be treated quickly, otherwise there is a danger to life. In principle, acute kidney failure - in contrast to chronic kidney failure - is reversible. This means that the kidney can also recover from an almost complete acute loss of function.
Acute kidney failure: symptoms
You can read about the symptoms acute kidney failure can cause in the article Kidney Failure - Symptoms.
Acute kidney failure: causes and risk factors
Depending on the cause, acute kidney failure is divided into the following forms:
Prerenal kidney failure
Prerenal kidney failure is due to decreased blood flow to the kidneys. The most common cause of this is blood and fluid loss due to major operations or accidents. Changes in kidney blood flow caused by certain drugs (X-ray contrast media, ACE inhibitors or antibiotics) can also cause prerenal kidney failure. In rare cases, heart failure (heart failure) or blood poisoning (sepsis) is the cause of reduced kidney blood flow and thus acute kidney failure.
Renal kidney failure
Renal-induced acute kidney failure is triggered by direct damage to kidney tissue. Such damage is caused, for example, by inflammation, for example non-bacterial kidney inflammation (glomerulonephritis) or vascular inflammation (vasculitis). Kidney infections with bacteria (pelvic inflammation) or viruses (interstitial nephritis) as well as toxic substances (e.g. certain antibiotics) can also damage the kidneys and thus trigger acute kidney failure.
Postrenal kidney failure
The cause of postrenal kidney failure is an obstruction to the flow of urine. For example, kidney stones, tumors and an enlarged prostate can interfere with the flow of urine and thus cause acute kidney failure.
Acute kidney failure: examinations and diagnosis
In order to diagnose acute kidney failure and determine the possible cause, the doctor will take the patient's medical history (anamnesis) and carry out various examinations:
Blood test
Typically, kidney values (creatinine and urea) rise in the blood in acute kidney weakness. The creatinine clearance is even more informative. It is how quickly the kidneys can filter creatinine out of the blood. In the case of kidney damage, it is already reduced at an early stage. In addition, there are changes in the blood salts, especially an increase in the potassium level. The blood count and other blood values (such as liver values, C-reactive protein, etc.) can also provide important information about acute kidney failure.
Urinalysis
The detection of protein in the urine, which is normally not or hardly to be found there, is very important for the diagnosis of "acute kidney failure". In addition, the glomerular filtration rate (GFR), the amount of urine, the specific gravity and the salt content of the urine are determined.
Ultrasound examination
An ultrasound scan (sonography) of the kidneys and the lower urinary tract is routine when examining a patient for acute kidney failure. If there is a postrenal kidney failure, the causing disruption of the urine flow (e.g. by a kidney stone) can be detected on ultrasound.
In some cases, more tests are needed to determine the cause of acute kidney failure, such as an x-ray of the kidney or taking a tissue sample (kidney biopsy).
Acute kidney failure: treatment
Acute kidney failure is treated in different ways, depending on the underlying cause. If, for example, kidney stones are responsible for acute kidney failure due to the obstruction of the urine flow, they must be removed. Bacterial inflammation is treated with antibiotics, the dosage of harmful drugs is reduced or discontinued entirely, and severe blood and fluid losses (e.g. due to accidents) are compensated for with infusions.
The administration of fluids in the form of infusions is generally important during the time in which the kidneys are recovering from the insufficiency. If acute kidney failure has (almost) completely paralyzed urine production, diuretics are also administered. If these measures do not improve the kidney function, the blood is artificially purified by blood washing (dialysis) until the kidneys can take over the blood purification and excretory function on their own again.
Acute kidney failure: prevention
During and after major operations, blood volume, blood pressure and fluid balance are closely monitored to reduce the risk of acute kidney failure.
Many drugs can cause kidney damage and thus trigger acute kidney failure. This also includes over-the-counter drugs such as certain pain relievers (e.g. paracetamol, ibuprofen, diclofenac). Therefore, you should discuss any drug use with the doctor. This is especially true for patients with existing kidney disease and impaired kidney function - they are particularly prone to acute kidney failure.
Acute kidney failure: disease course and prognosis
Acute kidney failure is a life threatening condition. Acute renal insufficiency is particularly common in intensive care patients - the mortality rate here is 50 to 80 percent.
If acute kidney failure is treated in good time and the patient is not weakened by other previous illnesses, the kidney function can also recover. Only in a few cases does the kidney function slowly deteriorate again as the disease progresses.
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