Kidney Failure

Kidney failure, also known as renal failure, is a medical condition in which the kidneys function at less than 15% of their normal levels. When the kidneys fail, they cause fluids and waste to build up in the body, leading to potentially severe symptoms.

The symptoms, causes, and treatment of kidney failure can vary depending on whether the condition is acute (rapidly developing) or chronic (long-term and gradually progressing). Despite the types, kidney failure requires immediate and sometimes urgent medical care.

This article explains what kidney failure is, including why it occurs and what is involved in the diagnosis and treatment. It also lists the signs and symptoms of an emergency so that you can seek appropriate care.

Symptoms of Kidney Failure

The kidneys are responsible for ridding the body of wastes, toxins, and excess fluids while returning hormones, glucose (blood sugar), minerals, and other important substances to the bloodstream.

When the kidneys fail, fluids, waste, and other substances can accumulate to harmful levels. At the same time, hormones normally produced by the kidneys can plummet due to the damage to the kidneys themselves. Both effects account for many of the symptoms of kidney failure.

Common symptoms include:

• Gradually diminishing urine output
• Swelling of the legs, ankle, or feet due to fluid retention
• Nausea
• Fatigue or tiredness
• Weakness
• Shortness of breath
• Chest pain or pressure
  
• Confusion

In severe cases, the accumulation of waste and toxins can lead to seizures and even coma.

Types of Kidney Failure

There are two types of kidney failure that share many of the same signs and symptoms. They mainly differ by the speed at which they develop as well as the underlying causes.

Acute kidney injury (AKI), formerly known as acute kidney failure, is the sudden but often reversible loss of kidney failure. AKI develops over the course of hours or days and most often occurs in people who are already critically ill.

Kidney failure can also occur as a result of chronic kidney disease (CKD). This is the type of kidney disease that progresses gradually, often with few symptoms until the disease is advanced. In fact, according to the Centers for Disease Control and Prevention (CDC), 2 out of 5 people with severe CKD (who are not on dialysis) do not even realize they have kidney disease.

When the kidney damage is so severe that dialysis (the mechanical filtration of body fluids) or a kidney transplant is needed to keep you alive, it is referred to as end-stage renal disease (ESRD). This can occur in some people with CKD as well as some people with severe AKI.

There is also a condition called acute-on-chronic kidney injury (ACKI), in which a person with CKD experiences an acute loss of kidney function. With ACKI, the acute cause of the failure may be reversed, but not the underlying chronic condition.

ACKI is concerning because it increases the risk of long-term dialysis by no less than twentyfold compared to AKI without CKD.

Causes of Kidney Failure

The causes of kidney failure differ by whether the underlying condition is acute or chronic. The distinction is important because the treatment and prognosis (projected outcomes) of each are different.

Acute Kidney Injury

AKI is mainly caused by the reduced flow of blood to the kidneys, usually in someone who is already unwell with another serious illness.

The reduced blood flow to the kidneys may be caused by:

• Hypovolemia: Low fluid volumes due to blood loss or severe dehydration, diarrhea, vomiting, or burns
• Heart failure: A condition in which the heart does not pump enough blood to service the body's needs
• Hepatorenal failure: A condition in which the loss of kidney function is related to damage caused by liver failure
• Renal artery thrombosis: A blood clot in one or both main arteries servicing the kidneys
• Sepsis: The spread of a local infection throughout the body that can trigger a steep drop in blood pressure

At other times, AKI is caused by a problem in the kidneys or the organs downstream of the kidneys, including the bladder, prostate gland, ureters (the tubes that connect the kidneys to the bladder), and urethra (the tube through which urine exits the body).

Causes of AKI involving the kidneys and urinary tract organs include:

• Bladder or kidney stones: Small, hardened deposits that can block the flow of urine
  
• Prostate cancer: Cancer of the prostate gland
• Pyelonephritis; A type of severe kidney infection
  
• Trauma: Including impact or crush injuries
• Vasculitis: A rare condition that can cause inflammation and narrowing of the blood vessels of the kidneys
• Urothelial carcinoma: The most common type of bladder cancer

Certain drugs are nephrotoxic (harmful to the kidneys). These tend to cause harm when used at higher doses over a long period.

The classes of nephrotoxic drugs most associated with AKI are:

• ACE (angiotensin-converting enzyme) inhibitors: Used to lower blood pressure
• Antibiotics: Used to treat bacterial infections
• Angiotensin-receptor blockers (ARBs): Used to lower blood pressure
• Chemotherapy drugs: Used to treat cancer
• Diuretics: Used to lower blood pressure (also known as water pills)
• Nonsteroidal anti-inflammatory drugs (NSAIDs): Used to reduce inflammation and pain
• Rifampin: Used to treat tuberculosis
• Tacrolimus: Used to prevent organ transplant rejection

End-Stage Renal Disease

Most cases of ESRD are caused by three conditions that either directly or indirectly damage the kidneys over time. In many cases, more than one cause is involved.

Some of the more common causes of ESRD are:

• Hypertension: Also known as high blood pressure, this is a chronic condition that can cause the hardening and narrowing of the blood vessels servicing the kidneys.
• Diabetes: Persistently high blood sugar levels can progressively damage the tiny filtering units of the kidneys, called glomeruli.
• Glomerulonephritis: This is the inflammation of glomeruli caused by bacterial infections (like pyelonephritis), viral liver diseases (like hepatitis C), and autoimmune diseases (like lupus or IgA nephropathy), among others.
  

How to Treat Kidney Failure

The treatment of kidney failure varies and depends on whether the cause is acute or chronic. The distinction is important because AKI can often be reversed, while kidney failure from CKD cannot.

Acute Kidney Injury

People with AKI almost always need to be treated in hospitals. Many, in fact, are already hospitalized for another condition when AKI occurs.

The focus of treatment is to either resolve or manage the underlying condition. Oftentimes, this can be done without causing permanent harm to the kidneys.

In addition, the medical team will deliver treatments to prevent AKI complications. This includes irreversible kidney damage—and even ESRD—if the treatment is delayed.

Treatment options for AKI include:

• Intravenous fluids: These are fluids that are delivered through a needle into a vein to restore fluid levels in people with hypovolemia,
• Diuretics: These can help remove excess fluids that can build in the lungs (causing pulmonary edema) and lower extremities (causing peripheral edema).
• Intravenous calcium: This is used to counteract a potentially severe condition called hyperkalemia caused by the excessive buildup of potassium in the bloodstream.
• Hemodialysis: This is a mechanical blood filtration system used to clear waste, toxins, and excess fluids from the bloodstream.

End-Stage Renal Disease

People with ESRD require either dialysis or a kidney transplant to stay alive.

Dialysis functions as a substitute for the kidneys. It is done by either filtering the blood (hemodialysis) or by using the lining of the abdominal cavity as a natural filter (peritoneal dialysis).

Hemodialysis is typically performed in a hospital or clinic, usually three times weekly for between three and five hours. There are newer home hemodialysis machines that can be used by certain individuals.

Peritoneal dialysis is performed manually at home but requires more frequent treatments (four to six 30-minute sessions per day, seven days a week). There are also continuous peritoneal dialysis machines that can filter waste and fluids while you sleep.

Dialysis can keep you alive and functioning until a kidney is available for transplant. A medical team will evaluate you to determine if you are a candidate for a transplant and place you on a national waiting list until a matched kidney can be found.

Are There Tests to Diagnose the Cause of Kidney Failure?

Kidney failure occurs when the kidneys are functioning at less than 15% of their normal values. This is determined by a test known as the estimated glomerular filtration rate (eGFR), which calculates how effectively the filters of the kidneys are able to remove waste.

Diagnosing the underlying cause of kidney failure may involve blood tests, urine tests, and imaging studies such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). These can help pinpoint the cause of the problem, whether it be an obstruction, infection, or injury.

A kidney biopsy may also be performed, which can help establish if there is an infection, an inflammatory condition, tissue necrosis (death), or cancer. This can usually be done by extracting a tissue sample through the wall of the abdomen with a needle (referred to as a percutaneous biopsy).

When to See a Healthcare Provider

Kidney failure, whether acute or chronic, requires immediate medical treatment.

You should seek medical care if you experience the following signs and symptoms of acute kidney failure:

• Too little or no urine leaving the body
• Swelling of legs, ankles, or around the eyes
• Shortness of breath
• Confusion
• Chest pain or pressure
• Seizure

If treated immediately with fluids and medications (and sometimes dialysis), AKI will often improve within a couple of days.

Among people with ESRD, dialysis or a kidney transplant are the only options for survival. Without dialysis, a person diagnosed with ESRD will typically live for seven to 10 days. With dialysis, many people can remain active and live for five to 10 years or even more.

Summary

Kidney failure occurs when the kidneys function at less than 15% of their normal levels. When this happens, the buildup of fluid and toxins can lead to symptoms such as nausea, decreased urination, fatigue, shortness of breath, and swelling of the feet and ankles.

Acute kidney injury (AKI) develops rapidly and is typically reversible, but it can lead to kidney failure. Kidney failure can also occur in people with a slowly progressive and irreversible form of kidney disease called chronic kidney disease (CKD). End-stage renal disease (ESRD) is when the kidney damage is so severe that dialysis or a kidney transplant is needed to stay alive.

AKI needs to be treated immediately in a hospital with fluids, medications, and possibly dialysis. ESRD requires either dialysis or a kidney transplant to stay alive.

A Word From Verywell

The symptoms of kidney failure can be easy to miss because many are nonspecific. Even so, it is important to respond quickly if you experience the spontaneous onset of symptoms like decreased urination, shortness of breath, and swelling of the ankles and feet. Without question, symptoms like these warrant urgent investigation.

Studies have shown that acute kidney failure, while typically reversible, can lead to ESRD, particularly if the symptoms are severe and diagnosis and treatment are delayed.

Even if your symptoms are mild or don't fit the profile for kidney failure. have them looked at anyway. When it comes to kidney failure, whether acute or chronic, it is better to be safe than sorry.