Acute kidney failure

Synonyms

• Acute renal failure
• sudden kidney failure
• ANV
• shock

Definition of kidney failure

Dem acute kidney failure (ANV) can have different causes, e.g. B .:

• acute glomerulonephritis
• Damage to the blood vessels in the kidneys (e.g. Vasculitis)
• Toxins and much more.

Often it arises after severe Injuries, operations, shock or sepsis (med. term for Blood poisoning). The prognosis for multiple organ failure is particularly poor.

In the context of acute kidney failure, the Function of the kidney so far reducedthat they have their No longer fulfilling tasks can.

Classification

There is a common classification according to the origin of the cause:

1. prerenal acute kidney failure
2. renal acute kidney failure
3. postrenal acute kidney failure

Acute kidney failure requiring dialysis occurs with a frequency of approx. 30 patients / 1 million inhabitants / year, with acute kidney failure not requiring dialysis occurring even more often.
Especially as part of multi-organ failure (failure of several internal organs at the same time) it occurs increasingly, especially in septic patients (= patient with blood poisoning) with systemic (= infection affecting the whole body) infection (Systemic Inflammatory Response Syndrome - SIRS).

Prerenal acute kidney failure is usually triggered by a severe volume deficiency (e.g. due to bleeding / blood loss) or as part of a shock. Particular emphasis should be given to its occurrence as part of multiple organ failure, which often affects septic patients (blood poisoning due to bacterial seedling). Other causes can be acute circulatory disorders such as arterial embolism, venous thrombosis (blood clot caused by blood clotting), i.e. occlusive diseases of vessels or an aneurysm (the circumscribed expansion of an arterial blood vessel).

Symptoms vary depending on the cause. These can be insidious so that the acute kidney failure is initially not recognized.
Urinary excretion is restricted (oliguria) or no longer present at all (anuria) and the resulting complications such as acidosis (acidosis), hyperkalemia (increase in potassium in the blood) and many more. The usability of the laboratory values ​​can be restricted by concomitant diseases of the liver, heart or kidneys, as well as by the administration of diuretics (drugs to stimulate kidney function (urine excretion)).

Renal acute renal failure is caused by acute glomerular (rapid progressive glomerulonephritis) and interstitial (interstitial nephritis) diseases (see kidney).
It can also be caused by toxins or vasculitis (inflammation of the blood vessels). Especially with the latter diseases, a tissue sample of the kidney (kidney biopsy) should be taken as early as possible for diagnostic clarification.
Haemolytic uremic syndrome (HUS) and acute kidney transplant rejection also belong to this group of causes.

The symptoms here are varied and usually include signs of a general illness such as:

• fever
• Skin changes
• Joint pain
• or anemia (anemia).

Postrenal acute kidney failure is caused by obstruction of the drainage in the urinary tract. The obstruction can lie within the ureter or compress it from the outside (e.g. prostate changes; see prostate).

This leads to cramp-like (colicky) pain in the area of ​​the lower urinary tract. The exact cause can usually be found out with an ultrasound examination.

The amount of urine excreted can often not be used to establish a diagnosis, since the key symptom oliguria (little urine excretion), as already mentioned above, may be missing.

Metabolic diseases, such as the storage disease Fabry's disease, often lead to kidney failure if left untreated!

Stages of kidney failure

To see the stages of Renal failure there are different classification systems to describe. If it is an acute impairment of the kidney function, the AKIN stages for use.AKIN stands for acute kidney injury, which means acute kidney failure. A distinction is made between stages 1-3. The staging is based on two parameters. Of the absolute urine output over a certain period of time and the Increase in creatinine.

Creatinine is a protein that is produced in the body and excreted through the kidneys. An increase in creatinine levels indicates decreased kidney function. Stage AKIN 1 occurs when creatinine increases by 1.5 to 2 times the normal value or increases by 0.3 mg / dl within 48 hours. Alternatively, an AKIN stage 1 is used if the urine excretion over 6 hours is less than 0.5 ml per kilogram of body weight per hour. If a man weighing 70 kg excretes less than 35 ml per hour (i.e. less than 210 ml in 6 hours) over 6 hours, then an AKIN stage 1 is present.
A AKIN stage 2 is present if the creatinine increase is 2 to 3 times the norm or if the urine excretion is less than 0.5 ml per kilogram of body weight over 12 hours. In our example, less than 420 ml urine is excreted in 12 hours.
At a AKIN stage 3 If there is a creatinine increase before which exceeds the norm by more than 3 times or if the creatinine value is above 4 mg / dl and there is an acute increase of> 0.5 mg / dl. Alternatively, with AKIN 3, urine excretion of less than 0.3 ml per kilogram of body weight per hour over 24 hours (in our example less than 504 ml in 24 hours) or there is anuria over 12 hours, i.e. there is no urine at all eliminated.

There are other classifications for classifying renal insufficiency, for example according to KDIGO and the one after the glomerular filtration rate (GFR). However, these two classifications deal with that chronic, not that acute kidney failure. There is a subdivision into 4 stages according to GFR and 5 stages according to KDIGO. The higher the stage, the more advanced the renal failure.

Symptoms

Acute kidney failure can often hardly be recognized by the person concerned and only at an advanced stage. It usually runs completely painless. There are courses of acute kidney failure with one Drying up of urine production goes hand in hand, one then speaks of one Anuria. Also a decrease in urine production less than 500 ml urine excretion per day (Oliguria) is possible. However, this is not always the case. There is also kidney failure with normal or even excessive urine production. Because the damaged kidneys accumulate substances that are normally sufficiently excreted, this can lead to hyperkalemia, among other things. Hyperkalemia means that too much potassium in the blood is available. This can be dangerous Cardiac arrhythmias to lead.
Impaired kidney function can also lead to a Overloading the organism with urinary substances lead, one then speaks of one Uremia.

Possible symptoms of uremia can Poor concentration and fatigue The symptoms can then range up to Disorientation and sleepiness increase. Other possible symptoms of acute uremia are nausea and Vomit such as itching. Overhydration can also be an indication of acute kidney failure. It can Water retention in the legs (Lower leg edema) or it can lead to overhydration of the lungs with the development of a Pulmonary edema come. This can get through Shortness of breath (Dyspnea) and rattling, "Bubbling" breath sounds express.

Pain

Pain does not occur with acute kidney failure. Therefore, the diagnosis is also much more difficult. The symptoms that occur in acute kidney failure are very diverse and unspecific.

Read here what to do when taking Painkillers for kidney diseases is to be observed

diagnosis

Blood tests (especially with a focus on laboratory values ​​such as: urea, creatinine, blood gases, acid-base status) and urine diagnostics provide crucial information.
An examination of the urine for excreted red blood cells (erythrocytes) and proteins (so-called proteinuria) must be carried out! This allows the location of the damage to be determined, which is of great importance for the further procedure.

Read more on the subject at: Kidney values

If the cause remains unclear, a kidney biopsy should be considered.

Alternative diseases that may be associated with similar causes are

• Glomerulonephritis
• acute deterioration of renal function in the context of chronic renal insufficiency
• acute bacterial nephritis

1. Renal cortex - Renal cortex
2. Renal medulla (formed by the
   Kidney pyramids) -
   Medulla renalis
3. Kidney bay (with filling fat) -
   Renal sinus
4. Calyx - Calix renalis
5. Renal pelvis - Pelvis renalis
6. Ureter - Ureter
7. Fiber capsule - Capsula fibrosa
8. Kidney column - Columna renalis
9. Renal artery - A. renalis
10. Renal vein - V. renalis
11. Renal papilla
    (Tip of the kidney pyramid) -
    Renal papilla
12. Adrenal gland -
    Glandula suprarenalis
13. Fat capsule - Capsula adiposa

You can find an overview of all Dr-Gumpert images at: medical illustrations

Causes of Kidney Failure

General

While that acute kidney failure often through acute Diseases, Injuries or Poisoning chronic kidney failure is usually the result of a long-standing underlying disease.

Causes of acute kidney failure

To the causes of a acute kidney failure To be more understandable, they have been divided into three categories:

• prerenales,
• intrarenales and
• postrenales acute kidney failure.

Here prerenal means "in front of the kidney", intrarenal means "within the kidney" and postrenal means "behind the kidney".

Prerenal kidney failure is caused by changes in the bloodstream in front of the kidney. Thus the kidney itself is not damaged at the beginning. Reasons for such kidney failure can be:

• massive volume losses, e.g. due to severe blood loss
• or a so-called shock kidney for circulatory instability.

This centralizes the circulation so that only the most important organs such as the heart and brain are supplied with oxygen. Both causes lead to insufficient blood flow to the kidneys and thus to an insufficient supply of oxygen, which causes kidney tissue to perish.
But kidney poisoning can also lead to its failure. The poisons cause a constriction of the blood vessels in the kidneys and thus also a lack of blood flow and thus an insufficient supply of oxygen.

Intrarenal kidney failure is caused by changes or diseases of the kidney itself. Causes for this are, for example

• a long-standing prerenal kidney failure,
• Blockage of the kidney ducts due to massive blood breakdown,
• Urates or one
• massive breakdown of muscle cells rhabdomyolysis. Also
• Blood clots or
• Metabolic diseases (e.g. Wegener's disease) can clog the vessels in the kidneys.

In addition to these causes, poisons and numerous drugs can also lead to tissue damage.

Postrenal acute kidney failure is caused by a shift in the urinary tract towards the kidney. The reasons for this are:

• Ureteral stones,
• congenital narrowing of the ureters,
• Obstruction of the bladder due to bladder tumors or
• but also blocked urinary catheters
• Constriction of the urethra caused by external tumors, such as a large prostate tumor.

Drugs that can cause acute kidney failure

A typical group of drugs that can cause kidney failure are Painkiller from the group of non-steroidal anti-inflammatory drugs. These include, for example, the widely used pain relievers Ibuprofen and Diclofenac. Taken occasionally, they rarely lead to kidney damage. However, if they are taken permanently over a long period of time or if the kidneys are clearly damaged, the ingestion can lead to an increasing loss of kidney function over time. The problem is that this loss is often only noticeable when a large part of the kidney function has already been lost. There are also drugs that can lead to acute kidney damage, even if only a small amount is taken some antibiotics and some drugs from the group of Chemotherapy drugs. However, it varies greatly from person to person which drug causes kidney damage in whom and how quickly this happens. The general rule is that in people with previously damaged kidneys extreme caution when choosing medication should prevail.
It is therefore essential to contact your doctor before you start taking new medication on your own.

Causes of Chronic Kidney Failure

The chronic kidney failure is, however, usually through a long-standing Underlying disease evoked.
Chronic kidney failure is particularly common as a result of poorly adjusted people Diabetes mellitus (Diabetes) or an untreated one High blood pressure (Hypertension).

Both underlying diseases lead to one slowly advancing Damage to the kidneywhich is no longer reversible after a while and leads to chronic kidney failure Dialysis requirement leads.
Especially patients with a combination of

• high blood pressure,
• Diabetes mellitus,
• Lipid metabolism disorder and
• Obesity (metabolic syndrome) have a significantly increased risk of chronic kidney failure.

But also chronic ones Inflammation of Kidney tissuewho have favourited regular ingestion of large amounts of various Painkiller over years or Tumor diseases of the kidney can trigger chronic kidney failure. Likewise, patients with a previous acute kidney failure have a significantly increased risk to suffer from chronic kidney failure.

Therapy kidney failure

If an existing acute kidney failure has been diagnosed, the most urgent measure is immediate Compensation for the lack of volume depending on the cause of the loss (bleeding, fluid loss through the gastrointestinal tract, burns, etc.).
It should also be sufficient Calorie intake (especially via glucose) should be respected, especially if dialysis is required.

MedicationDopamine, as well as loop and osmotic diuretics (water-draining drugs) should be stopped now as they can be dangerous.

Since the body can only tolerate the supply of fluids to a limited extent, hypertonic infusion solutions must be administered (supply of fats).

Renal replacement therapy is unavoidable if laboratory values ​​and clinical signs are appropriate. Generally, this should be started when:

• Hyperkalemia (from 6.5 mmol / l) = too high levels of potassium in the blood
• urea > 180 - 200 mg / dl
• Creatinine> 8 mg / dl
• Uremic symptoms such as pericarditis (inflammation of the pericardium), nausea, encephalopathy (poisoning from brain)
• Pulmonary edema, untreatable hypervolemia
• severe hyperphosphataemia (too high a level of phosphate in the blood), especially with concomitant hypercalcaemia (calcium too high in blood)

As options of kidney replacement therapy are available Hemodialysis / dialysis, hemofiltration and Hemodiafiltration to disposal.

forecast

As part of a higher-level disorder affecting several organs (such as in the context of multiple organ failure), acute kidney failure (AVN) still has a high mortality rate (> 75%) today.

The real, d. H. only on the kidney related, prognosis is quite good. The transition to chronic kidney failure occurs only rarely.
If the urine output is preserved, the prognosis is even more favorable. In acute kidney failure with causes such as circulatory disorders or toxins, a phase-like course can occur:

1. Oliguria / anuria (little or no urine output)
2. Polyuria (too much urination)
3. normalization of kidney function

The time between the individual sections is variable.
Acute kidney failure (AVN) can also be fraught with numerous complications.
The water and electrolyte balance (potassium, calcium) as well as the acid-base balance of the organism are severely disturbed by the drying up of urine excretion. The fluid overload manifests itself through Edema and hypertension (high blood pressure).
In this context, the "fluid lung" is particularly dangerous, i. H. Difficulty breathing due to water (interstitial edema) in the lungs, which can only be seen on X-rays.

Furthermore, hyperkalaemia (too high potassium levels in the blood) can set in, which is to be assessed as an emergency, as it can develop very quickly. It is favored by metabolic acidosis (over-acidification due to insufficient H + excretion via the kidneys) and can become severe from values ​​of 7 mmol / l Cardiac arrhythmias to lead.

Furthermore it can be Gastric ulcer (Ulcus ventriculi) and Duodenal ulcer (duodenal ulcer) and associated bleeding.

Read more about the topic here: Life expectancy with kidney failure