Acute renal failure (ARF) is when a person’s kidneys are not working as well as they once did. This usually happens very suddenly over several hours or up to 2 days. Treatment can depend on the underlying cause.

As a result of acute renal failure (ARF), the kidneys do not filter and dispose of waste products as they should, and a person’s urine output often falls.

Ideally, a doctor will identify ARF immediately, and treatment can begin to reverse the underlying causes.

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Pressure or pain in the chest may be a symptom of ARF.

Often, a person will experience ARF when they have another serious illness, such as pneumonia or sepsis.

As a result, they may not observe the symptoms of ARF immediately.

Some symptoms of ARF causes include:

  • urine that is very dark
  • confusion
  • lower urine output
  • itching skin or skin rashes from waste buildup
  • pressure or pain in the chest
  • shortness of breath
  • swelling in the lower extremities
  • unexplained nausea

Some people may experience severe side effects, including seizures and loss of consciousness.

Doctors will usually classify ARF in one of three stages, depending on test results and a person’s urine output. Stage 1 is the least severe while stage 3 is the most severe.

A research paper in the journal American Family Physician outlines the stages, as follows:

Stage 1

A person in stage 1 ARF experiences a sudden increase in their serum creatinine, a kidney waste product, by 0.3 milligrams per deciliter (mg/dl), or an increase of 1.5 to two times from their baseline.

The person will also produce fewer than 0.5 milliliters per kilogram (ml/kg) of their body weight per hour for 6 hours or more.

Stage 2

A person in stage 2 ARF will have an increase in their creatinine level that is two to three times their baseline. They will also have a urine output of fewer than 0.5 ml/kg of their body weight for 12 hours or more.

Stage 3

A person will have a creatinine level that is three times their baseline, or that is greater than 4.0 mg/dl. They will produce no urine for 12 hours or fewer than 0.3 ml/kg for 24 hours.

Due to its severity, this stage will require immediate renal replacement therapy, a continual form of dialysis.

Typically, a doctor will start prescribing interventions before a person’s ARF progresses to stage 3.

People who are ill and receiving medical treatment in a hospital are particularly at risk of ARF. This is especially true of those in an intensive care unit (ICU) setting.

Research has estimated that as many as 7 percent of all patients in the hospital and 66 percent of those in an ICU will experience ARF.

Doctors also use three categories to classify the causes of ARF:

  • Pre-renal: Something is affecting blood flow to the kidneys, and these organs are unable to work correctly. Examples of these causes include low blood pressure, excess blood loss, and dehydration.
  • Post-renal: Something is blocking the ureters where urine leaves the kidneys, which is affecting how the organs work. Underlying causes of this include kidney stones, cancer, and an enlarged prostate in men.
  • Intrinsic renal: A medical condition damages the kidneys, or something inside is not working as well as it once did. Common causes of this include kidney infections, blood clots in the kidneys, or other medical conditions. Taking medications known to damage the kidneys can also be a cause.

Medications that can damage the kidneys include:

  • rifampin
  • phenytoin (Dilantin)
  • proton pump inhibitors
  • nonsteroidal anti-inflammatory drugs (NSAIDs)

Ideally, a doctor will be able to identify the underlying cause of a person’s ARF quickly. This means they can recommend treatment to prevent an acute condition from becoming chronic renal failure.

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A person who has severely affected kidney function may need dialysis.

The treatment for ARF depends on what is causing the condition. With many potential reasons for ARF, there are also many treatments.

An example is when a person has significant blood loss from injury or illness, and then doctors may administer blood products and fluids to restore the blood volume.

Doctors will also limit the use of medications known to be toxic to the kidneys, such as contrast dye and some antibiotics.

If a person has an active bacterial infection, a doctor may prescribe antibiotics.

People who have very low blood pressure may need special medications to maintain their blood pressure. Doctors usually give these drugs intravenously.

People who have severely affected kidney function may require dialysis.

Dialysis is when a machine acts as an artificial kidney to filter a person’s blood for waste products and fluid removal until their kidney function improves.

Some of the risk factors for ARF that doctors have identified include:

If a person has gone through ARF in the past, they are more likely to have it in the future. They are also at greater risk for other health complications, such as stroke, heart disease, kidney disease, or heart disease.

It is not always possible to prevent ARF. However, there are some steps a person can take to minimize their risk.

These steps include:

  • Following a healthful diet and keeping blood sugar levels at their desired target if someone has diabetes.
  • Maintaining a healthy blood pressure through diet, exercise, and medications, if necessary.
  • Avoiding excessive use of medications that the kidneys filter, especially ibuprofen and aspirin. Excess amounts of these medicines can damage the kidneys.

ARF or acute kidney injury can quickly become serious if left untreated. Recognizing that a person is not producing as much urine as they should, or that their symptoms could indicate slowing kidney performance is vital.

If a person thinks they are having signs of ARF, they should talk to their doctor immediately.