Acute renal failure (ARF) is an older term commonly used for what is now generally called acute kidney injury (AKI).

It describes a sudden deterioration in kidney function that can develop over hours or days. The kidneys may temporarily become less effective at removing waste products, regulating fluid balance and maintaining normal electrolyte and acid-base levels.

AKI is different from chronic kidney disease because the decline occurs over a relatively short period. It can sometimes be reversible when the underlying cause is identified and treated promptly.

Current kidney-care guidance emphasizes early recognition, identifying the cause and managing factors that may worsen kidney injury. KDIGO's current AKI guidance is also being updated to incorporate newer approaches to detection, prevention, fluid management, medication safety and kidney replacement therapy.

At Prabhakar Bhurke Clinic, Dr. Sandip Prabhakar Bhurke, super specialist nephrologist and transplant physician, provides evaluation and management for acute changes in kidney function.

Acute Renal Failure vs Acute Kidney Injury

The terms acute renal failure and acute kidney injury are sometimes used interchangeably in everyday medical discussions.

However, acute kidney injury is the preferred modern terminology because the condition can range from a relatively mild reduction in kidney function to severe kidney failure requiring kidney replacement therapy.

AKI is diagnosed using changes in serum creatinine and/or urine output rather than waiting for complete loss of kidney function. KDIGO criteria include a creatinine increase of at least 0.3 mg/dL within 48 hours, an increase to at least 1.5 times baseline within seven days, or sufficiently reduced urine output.

What Causes Acute Renal Failure?

AKI can develop from problems occurring before the kidneys, within the kidneys or after the kidneys.

1. Reduced Blood Flow to the Kidneys

The kidneys need adequate blood flow to filter blood.

Reduced circulation may occur with:

• Severe dehydration

• Heavy blood loss

• Severe vomiting or diarrhea

• Major burns

• Very low blood pressure

• Severe infection or sepsis

• Heart-related conditions

• Major surgery

This pattern is often referred to as prerenal AKI.

2. Direct Kidney Injury

The kidney tissue itself can become damaged.

Possible causes include:

• Certain medicines

• Toxic substances

• Severe infections

• Acute tubular injury

• Glomerular inflammation

• Interstitial nephritis

• Autoimmune disease

• Severe muscle injury and rhabdomyolysis

The exact treatment depends on which part of the kidney has been affected.

3. Urinary Tract Obstruction

A blockage can prevent urine from draining normally.

Potential causes include:

• Kidney or ureteral stones

• Enlarged prostate

• Ureteral narrowing

• Tumors or masses

• Blood clots

• Other structural abnormalities

This is sometimes called postrenal acute kidney injury.

Removing or relieving the obstruction can allow kidney function to improve when the damage is reversible.

What Are the Symptoms of Acute Renal Failure?

Symptoms vary according to the severity and cause of AKI.

Possible signs include:

• Reduced urine output

• Very little or no urine

• Swelling of the legs, feet or face

• Sudden weight gain from fluid retention

• Breathlessness

• Nausea

• Vomiting

• Loss of appetite

• Fatigue

• Weakness

• Confusion

• Difficulty concentrating

• Muscle cramps

Some people with AKI may have few obvious symptoms, especially during the early stages.

For this reason, kidney-function blood tests can be important when AKI is suspected.

Can Acute Kidney Injury Occur Without Complete Kidney Failure?

Yes.

The term acute kidney injury covers a range of severity.

A patient may have a measurable deterioration in kidney function without completely losing the ability to produce urine or without immediately requiring dialysis.

Early detection matters because AKI can be treatable and may have better outcomes when the underlying cause is addressed promptly.

How Is Acute Renal Failure Diagnosed?

Diagnosis usually involves combining laboratory results with the patient's history and clinical examination.

Serum Creatinine

Creatinine is commonly monitored to identify a change from the patient's baseline kidney function.

A single creatinine value does not always reveal when the injury started, so previous results can be particularly useful.

Urine Output

Doctors may monitor the amount of urine produced over time.

A significant reduction in urine output is one of the criteria used in AKI assessment.

Blood Tests

Depending on the clinical situation, testing may include:

• Urea

• Electrolytes

• Potassium

• Sodium

• Bicarbonate

• Blood count

• Calcium

• Phosphorus

These tests can identify complications and help guide treatment.

Urine Examination

Urinalysis may provide clues about:

• Blood

• Protein

• Infection

• Inflammation

• Other kidney abnormalities

Ultrasound or Other Imaging

Kidney and urinary tract imaging may be recommended when obstruction, stones or structural abnormalities are suspected.

Additional Tests

Depending on the suspected cause, doctors may order autoimmune testing, infection-related tests, specialized urine studies or, in selected cases, a kidney biopsy.

How Is Acute Renal Failure Treated?

There is no single medicine that treats every case of acute renal failure.

Treatment is directed at the underlying cause and the complications of AKI.

Correcting Dehydration or Low Circulating Volume

If reduced kidney blood flow is caused by fluid loss, appropriate fluid replacement may be necessary.

However, fluid treatment must be individualized. Giving large amounts of fluid to someone who is already fluid overloaded can be harmful.

Treating Infection

Severe infection or sepsis can cause AKI.

When infection is identified, appropriate antimicrobial treatment and management of the underlying infection are important.

Reviewing Medicines

Some medicines can contribute to kidney injury in susceptible patients.

A doctor may review prescription medicines, over-the-counter drugs and supplements and make adjustments when appropriate.

Patients should not stop important medicines independently.

Relieving Urinary Obstruction

If a stone, prostate problem or another blockage is responsible, restoring urine drainage may be necessary.

Depending on the cause, treatment may involve a ureteral stent, nephrostomy or another procedure.

Treating Specific Kidney Diseases

Glomerulonephritis, interstitial nephritis, autoimmune kidney disease and other intrinsic kidney conditions require diagnosis-specific treatment.

In selected cases, specialist treatment may include immunosuppressive medicines or other targeted therapies.

What Are the Stages of Acute Kidney Injury?

AKI is commonly classified into three stages according to changes in creatinine and urine output.

AKI stage	General criteria
Stage 1	Creatinine rises by at least 0.3 mg/dL or to 1.5–1.9 times baseline, or urine output is reduced for the specified period
Stage 2	Creatinine reaches about 2.0–2.9 times baseline or urine output remains significantly reduced
Stage 3	Creatinine reaches at least 3 times baseline, reaches specified severe levels, kidney replacement therapy is initiated, or urine output becomes severely reduced

The exact staging criteria should be interpreted by a healthcare professional using the patient's baseline results and clinical condition.

Can Acute Renal Failure Recover?

Yes, recovery is possible in many cases.

The outcome depends on:

• Cause of AKI

• Severity of kidney injury

• Speed of treatment

• Age and overall health

• Presence of sepsis or other serious illness

• Previous kidney function

• Duration of kidney injury

• Development of complications

Some patients recover kidney function completely.

Others recover partially and may be left with reduced kidney function.

Severe AKI can also increase the long-term risk of chronic kidney disease, which is why follow-up after recovery is important. Current KDIGO work on AKI and acute kidney disease emphasizes follow-up after AKI to identify longer-term kidney risks.

Does Acute Renal Failure Always Require Dialysis?

No.

Dialysis or another form of kidney replacement therapy is not automatically required simply because creatinine becomes high.

Kidney replacement therapy may be considered when complications cannot be adequately controlled with medical treatment.

Examples include:

• Severe or persistent hyperkalemia

• Severe metabolic acidosis

• Significant fluid overload causing breathing problems

• Certain uremic complications

• Selected toxin or poison exposures

• Severe kidney dysfunction with clinically important complications

The decision depends on the complete clinical situation rather than one laboratory value.

Acute Renal Failure and High Potassium

AKI can interfere with potassium excretion.

A dangerously elevated potassium level can affect the heart and may become life-threatening.

People with AKI therefore require appropriate laboratory monitoring, especially when urine output falls or medications and medical conditions increase potassium risk.

Severe potassium abnormalities require urgent medical treatment.

Acute Renal Failure and Fluid Overload

When the kidneys cannot remove sufficient water and sodium, fluid may accumulate.

This can result in:

• Swollen legs

• Facial puffiness

• Rapid weight gain

• Breathlessness

• Pulmonary edema

Significant fluid overload may require urgent treatment and, in severe cases, kidney replacement therapy.

Patients should not attempt to correct kidney-related fluid overload by drinking more water.

What Medicines Can Cause Acute Kidney Injury?

Several types of medicines can contribute to AKI in susceptible patients, particularly in the presence of dehydration, low blood pressure or other kidney stress.

Examples can include:

• Certain NSAID painkillers

• Some antibiotics

• Certain contrast-related exposures

• Selected blood-pressure medicines in particular clinical circumstances

• Other potentially nephrotoxic drugs

This does not mean that every medicine in these categories is unsafe for every patient.

Medication decisions should be individualized by the treating clinician.

Can Dehydration Cause Acute Renal Failure?

Severe dehydration can reduce blood flow to the kidneys and contribute to AKI.

Possible causes of significant fluid loss include:

• Persistent vomiting

• Severe diarrhea

• Fever

• Heavy sweating

• Poor fluid intake

• Significant blood loss

People with heart failure, advanced CKD or other fluid-sensitive conditions should not automatically increase fluid intake without medical advice.

Acute Renal Failure From Urinary Obstruction

A blocked urinary tract can cause postrenal AKI.

Potential causes include stones, prostate enlargement, strictures and masses.

When obstruction is suspected, imaging can help identify the location and severity of the blockage.

If the obstruction is causing significant kidney dysfunction, restoring urine drainage may be an important part of treatment.

What Happens After Acute Kidney Injury Improves?

Recovery does not necessarily mean that follow-up can stop immediately.

Kidney function may need to be monitored after AKI to determine whether:

• Creatinine has returned toward baseline

• eGFR has recovered

• Protein or blood remains in urine

• Blood pressure has changed

• Chronic kidney disease has developed or been unmasked

Long-term monitoring is particularly important after severe AKI.

How Can Acute Kidney Injury Be Prevented?

Not every episode of AKI can be prevented, but some risks can be reduced.

Helpful measures may include:

• Avoiding unnecessary NSAID use

• Maintaining appropriate hydration

• Treating serious infections promptly

• Monitoring kidney function when medically indicated

• Reviewing medicines during acute illness

• Managing diabetes and blood pressure

• Addressing urinary obstruction promptly

• Informing healthcare professionals about existing kidney disease

• Following medical advice before procedures involving potential kidney risks

People with CKD may require additional precautions.

When Is Acute Renal Failure an Emergency?

Seek urgent medical attention if there is:

• Very little or no urine

• Severe breathlessness

• Chest pain

• Confusion

• Severe weakness

• Persistent vomiting

• Rapidly increasing swelling

• Severe dehydration

• Sudden major deterioration in health

AKI can become serious quickly, particularly when it is associated with infection, severe electrolyte abnormalities, fluid overload or obstruction.

Acute Renal Failure Evaluation at Prabhakar Bhurke Clinic

At Prabhakar Bhurke Clinic, Dr. Sandip Prabhakar Bhurke, super specialist nephrologist and transplant physician, provides individualized evaluation for patients with sudden changes in kidney function.

Depending on the clinical situation, assessment may include:

• Review of previous creatinine values

• AKI staging

• Urine-output assessment

• Electrolyte evaluation

• Urine testing

• Medication review

• Assessment for dehydration

• Infection evaluation

• Investigation for urinary obstruction

• Kidney imaging when appropriate

• Management of kidney complications

• Assessment for kidney replacement therapy when indicated

• Follow-up of kidney recovery

The treatment strategy is based on the cause and severity of kidney injury rather than on creatinine alone.

Frequently Asked Questions

What is acute renal failure called now?

Acute renal failure is commonly referred to as acute kidney injury (AKI). The modern term recognizes that kidney injury can range from relatively mild dysfunction to severe kidney failure.

What is the main cause of acute renal failure?

There is no single cause. Severe dehydration, infection, low blood pressure, medicines, direct kidney diseases and urinary obstruction are among the possible causes.

Can acute renal failure be reversed?

Yes, some cases are reversible, particularly when the underlying cause is identified and treated promptly. Recovery may be complete or partial depending on the severity and cause.

Does acute renal failure mean dialysis is necessary?

No. Dialysis is used when kidney dysfunction produces complications that cannot be adequately controlled through other treatment.

How long does acute renal failure last?

The duration varies widely. Some patients improve over days, while more severe injuries may take weeks or longer to recover. Some patients are left with persistent kidney impairment.

Can acute kidney injury become chronic kidney disease?

Yes. AKI can increase the risk of later CKD, even when the initial episode improves. Follow-up kidney-function testing may therefore be important.

What tests are used for acute renal failure?

Common assessments include serum creatinine, eGFR, urea, electrolytes, urine testing, urine output monitoring and imaging when obstruction or another structural problem is suspected.

Conclusion

Acute renal failure, now more commonly called acute kidney injury, is a sudden decline in kidney function that requires timely evaluation. It can result from dehydration, infection, low blood pressure, medicines, direct kidney disease or urinary obstruction.

The most important step is to identify the cause and address it as early as possible. Treatment may involve correcting fluid or blood-flow problems, treating infection, adjusting medicines, relieving obstruction or managing a specific kidney disease.

Not every patient with AKI requires dialysis, and kidney recovery is possible in many cases. However, severe AKI can produce dangerous complications and may increase the future risk of chronic kidney disease.

For specialist evaluation of acute kidney injury and changing kidney function, consult Dr. Sandip Prabhakar Bhurke at Prabhakar Bhurke Clinic.

Medical Disclaimer

This article is intended for general educational and informational purposes only and should not be considered a substitute for medical diagnosis, treatment or individualized medical advice. Acute renal failure is now generally referred to as acute kidney injury and can have many different causes. Treatment must be based on the patient's symptoms, kidney-function results, urine output, medications, fluid status, electrolyte levels, imaging and underlying medical condition. Do not independently stop prescription medicines, increase or restrict fluids, take painkillers or start supplements to treat suspected kidney injury. Dialysis should only be started when clinically indicated by the treating medical team. Seek urgent medical attention for very little or no urine, severe breathlessness, chest pain, confusion, persistent vomiting, severe weakness, rapidly worsening swelling or sudden deterioration in health. Consult Dr. Sandip Prabhakar Bhurke or another qualified nephrologist for personalized evaluation.