Acute Kidney Failure

Acute kidney failure is a life-threatening emergency that requires the fastest possible therapy. Read about the vital functions our kidneys perform and the symptoms that indicate kidney failure. You will also learn everything you need to know about diagnosis, therapy, and prevention of acute kidney failure.

When the kidneys do their job no longer or only very incompletely, doctors speak of kidney failure. A distinction is made between two forms of progression: acute kidney failure (ANV) and chronic kidney failure (CRF). Acute kidney failure develops within hours to days and usually heals without consequences once the cause has been eliminated. In chronic kidney failure, the disease progresses slowly over months to years and, if left untreated, leads to death.

Function Of The Kidneys

Healthy people have two kidneys, one on the left and one on the right. Both kidneys perform important tasks in the body:

    • Excretion of metabolic end products (so-called urinary substances) and drugs
    • Keeping the water balance constant
    • Regulation of the electrolyte balance
    • Maintaining the acid-base balance
    • Production of hormones (such as erythropoietin and renin)
    • Conversion of inactive to active vitamin D.
    • Blood pressure regulation.

The kidneys as an excretory organ

Around 1500 liters of blood flow through the kidneys every day. Every day they excrete about one and a half liters of urine, which is filtered out of the blood. The blood flows through special filter systems (nephrons). A healthy kidney contains about 1 million such nephrons. In these filters, substances that the body no longer needs are, so to speak, sifted out of the blood (so-called urinary substances). If the urinary substances remain in the blood, they will poison the body. On the other hand, the nephrons also hold back important substances in the body. Above all, this includes proteins and electrolytes.


The symptoms of acute kidney failure are different. In any case, the main symptom is the significantly reduced amount of urine that is excreted. Sometimes no water can be left at all. In the course of decreasing urine production, the overhydration of the body increases. The consequences are, for example, water retention in the legs (edema) and in the lungs (pulmonary edema). Furthermore, life-threatening electrolyte disturbances (e.g. increased blood potassium concentrations) and life-threatening acidosis (acidosis) can occur. These make z. B. in the form of cardiac arrhythmias, nausea, and vomiting as well as rapid fatigue noticeable. If fluid builds up in the brain, the patient’s behavior can change. Psychological abnormalities such as excessive tiredness, indifference to impaired consciousness are indicative.


Doctors classify the causes of acute kidney failure as follows:

    • Prerenal ANV: In a maximum of 60 percent of cases, the cause of the kidney failure lies before the kidney (i.e. prernally). Often this is a suddenly greatly reduced blood flow to the kidneys, for example, due to circulatory shock in accidents or operations, due to blood clots in the kidney arteries, or due to drug side effects.
    • Intrarenal or renal ANV: Here the cause lies in the kidney itself (i.e. intra-renal). Triggers are damaged kidney tubules due to long-term lack of oxygen, damage from drugs or contrast media, and, rarely, severe inflammation of the kidney function bodies (so-called glomerulonephritis).
    • Postrenal ANV: The cause is an obstruction of the flow of urine behind the kidney (i.e. post-renal). The main obstacles to the outflow of urine are enlarged prostates, kidney, bladder, or urinary tract stones, inflammations, or tumors.


To diagnose acute kidney failure, the doctor must first clarify whether it is acute kidney failure or chronic kidney failure. The ANV is easier to recognize: The lack of urine production quickly gives the decisive clue.

Further diagnostic methods are anamnesis (i.e. questioning the patient), physical examination with listening to the heart and lungs, and laboratory tests. In particular, urinary substances such as creatinine and urea are determined in the blood. Test strips help with the urine examination. They record proteins, red and white blood cells, nitrite as an indication of a urinary tract infection, the urine pH value, glucose, ketone bodies, and bile pigments. This is followed by an examination of the urine in the laboratory.

The imaging methods used are ultrasound (sonography) and color Doppler sonography of the kidneys as well as X-rays of the chest with the heart and lungs. If the cause is inflammatory, a kidney biopsy may be performed. In this examination, a tissue sample is taken from the kidney during an endoscopic procedure.



The therapy of acute kidney failure depends primarily on the cause. This includes the following steps in particular:

    • Compensate for lack of fluids (if necessary with infusions)
    • raise low blood pressure (with medication if necessary)
    • Stop or switch drugs (such as antibiotics, pain relievers, and X-ray contrast agents) that have caused acute kidney failure
    • Surgically remove obstructions to the flow of urine (e.g. bladder or urethral stones, enlarged prostate, tumors).

Medical therapy

In acute kidney failure, your doctor can try to stimulate the excretory function with medication. For this purpose, so-called loop diuretics such as furosemide, piretanide, and torasemide are primarily administered. Alternatively, dehydrating agents of the thiazide-type such as hydrochlorothiazide and xipamide or potassium-sparing agents such as spironolactone can also be used.


If it is not possible to stimulate the kidney function again with medication, the phase until the kidneys produce urine independently must be bridged with a kidney replacement procedure (dialysis).


Sometimes drug therapy and dialysis are not enough to restore or replace kidney function to a sufficient extent. In these rare cases, a kidney transplant may be necessary.


The chances of recovery are very good if the cause of the acute kidney failure does not lie in the kidney itself. This is the case with prerenal and postrenal kidney failure.

Acute intrarenal kidney insufficiency is much less treatable, as more or less kidney tissue has been lost to varying degrees and irretrievably in this form. Acute intrarenal forms often lead to chronic renal failure. In addition, the complication rate (dialysis requirement) is significantly higher.

In many cases, serious illnesses, accidents or poisoning (also due to medication) are the cause of acute kidney failure. In these cases, up to 50 percent of those affected do not survive. The main cause of this is not kidney failure, but the circumstance that caused this failure.


Many over-the-counter drugs can damage the kidneys and cause acute kidney failure. Examples of this are popular over-the-counter drugs such as the pain relievers diclofenac, ibuprofen, and paracetamol or gastric acid inhibitors from the group of proton pump inhibitors. Therefore, you should not take pain relievers in particular for longer than recommended. In principle, it is advisable to discuss any prolonged use of medication with a doctor.

Stomach Acid Blockers Involve Risks

Proton pump inhibitors such as esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole are among the best-selling drugs in Germany. According to the drug report of the Barmer health insurance company, almost 12 million German proton pump inhibitors were prescribed in 2018. In addition, the active ingredients omeprazole, pantoprazole, or esomeprazole are also available over the counter. In public perception, gastric acid blockers from the active ingredient group of proton pump inhibitors are considered to be simple and safe drugs. However, two aspects are left out: the side effects and the fact that proton pump inhibitors can be addictive.

Kidney Damage as a Side Effect

The most common side effects of proton pump inhibitors include bone loss (osteoporosis) and magnesium deficiency with an increased risk of cardiac arrhythmias and seizures. These side effects have now been proven by a number of studies. It is even more serious that the medication permanently disrupts the natural regulatory cycle of gastric acid production. After prolonged use, between 14 and 64 percent of patients remain permanently dependent on the medication.

The connection between proton pump inhibitors and allergies is possible

Proton pump inhibitors may increase the risk of allergic diseases. Scientists from the University of Vienna published a study in the specialist magazine “Nature Communications” (August 2019) (see sources) that at least produced a striking statistical connection between the long-term use of proton pump inhibitors and allergic diseases. The scientists had evaluated data from Austrian health insurance companies. They found that the likelihood of prescribing antiallergic drugs increases by up to 300 percent if gastric acid blockers were previously prescribed. This does not necessarily mean that proton pump inhibitors actually trigger or promote allergies. In the opinion of the study authors, however, the connection cannot be dismissed out of hand and suggests that gastric acid blockers should only be used in very dosed quantities.

The German Society for Gastroenterology, Digestive and Metabolic Diseases assessed the study results differently. According to the press release, the specialist society does not see an “obvious connection between gastric acid blockers and allergies”. The design of the Austrian study does not give a corresponding assessment.