Acute renal failure comes on suddenly, usually in people who are already critically ill. Chronic kidney disease develops gradually and may not cause symptoms until much later. Treatments differ, but both may involve dialysis.

Acute renal failure (ARF) and chronic kidney disease (CKD) are two serious kidney-related conditions. While ARF has a rapid onset, CKD develops more gradually.

Learn more about the key differences between ARF and CKD, including the causes, symptoms, and overall outlook.

Also called acute kidney injury or acute kidney failure, ARF describes sudden and severe kidney damage or failure. It develops from a buildup of waste in your bloodstream that the kidneys can’t get rid of as they should.

ARF develops over a few hours and up to a few days. A doctor may diagnose ARF with a combination of blood and urine tests and possibly an ultrasound of the kidneys.

The possible causes of ARF include:

CKD is another type of kidney condition characterized by damage to your kidneys. But unlike ARF, CKD develops more gradually. ARF may also be a risk factor for developing CKD, and vice versa.

With CKD, your kidneys become unable to filter wastes from your bloodstream. This can lead to other health complications, such as heart disease.

Some possible causes of CKD include:

To diagnose CKD, having multiple test results over time helps determine whether kidney damage is acute or chronic. A doctor may use any of the following tests:

A low GFR rate can indicate problems with your kidneys. The presence of some proteins in your blood or urine could mean your kidneys are damaged.

ARF is most common in older adults and people already in the hospital for a critical illness. The risk of CKD may also increase with age, but it always develops more gradually.

Experts estimate that 37 million U.S. adults have CKD. Also, it affects roughly 1 in 5 adults with high blood pressure and 1 in 3 adults with diabetes.

While symptoms may vary, some of the most common ones associated with ARF include:

Unlike ARF, CKD usually doesn’t have symptoms at first. As kidney damage progresses, CKD may cause swelling in your legs and feet due to fluid buildup.

Other CKD symptoms could indicate that the condition is in an advanced stage. Possible signs include:

Most people with ARF require hospitalization. You may already be in the hospital before developing an ARF. The length of your hospital stay depends on the severity of ARF and the treatment response. A doctor may also recommend dialysis.

The focus of treatment for CKD is to prevent any kidney damage from worsening. Depending on the underlying cause of your condition, this may include treating and managing diabetes or high blood pressure.

You may require dialysis or a kidney transplant in later stages.

Having ARF increases your risk for:

  • a future incidence of ARF
  • developing CKD (possibly within 1 year)
  • heart disease
  • stroke

CKD may also lead to the above complications, as well as:

  • anemia
  • malnutrition
  • bone diseases

Doctors further diagnose CKD as stage 1 to 5, with lower stages indicating milder disease. Stages 4 and 5 are considered the most severe forms of CKD. At this point, you may need dialysis or a kidney transplant because your kidneys are no longer functional.

You may be able to help protect your kidneys with the following steps:

Below is a quick look at the key differences between ARF and CKD you may wish to discuss further with a doctor.

CausesSudden kidney injuryKidney damage that develops more gradually
Risk factorsA critical injury or illness; older age; hospitalizationHigh blood pressure, diabetes, or heart disease; family history
SymptomsDevelop suddenly and may include decreased urination, swelling, and confusionSymptoms develop over time and may include weight loss, brain fog, fatigue, and more
TreatmentHospitalization and dialysisManaging the underlying causes; dialysis or kidney transplant for later stages