Symptoms and diagnosis

Acute kidney failure—when kidneys suddenly stop working

Patients are sometimes confused about the difference between acute kidney failure and chronic kidney failure. Chronic kidney failure is a condition where the kidneys’ ability to filter waste from the bloodstream becomes worse over time, generally a period of years. 

Acute kidney failure is the sudden loss of this important ability. Although the condition can be life threatening, it can also be reversible. Patients whose kidneys have suffered from a direct injury or an obstruction are at risk. According to American Family Physician, 5% of hospitalized patients develop this condition.

What is acute kidney failure?

Acute kidney failure is the sudden and dramatic loss of kidney function. This condition develops rapidly, often in just a few days. 

Healthy kidneys filter and remove wastes and excess fluid from blood and turn it into urine. When one suffers from acute kidney failure, the kidneys are operating at less than 10% of normal function. This means wastes such as creatinine and urea nitrogen build up in the bloodstream. If this waste is not removed, a person will feel extremely ill.

What causes acute kidney failure?

Acute kidney failure may occur for a variety of reasons.  A “crush-” type injury may damage internal organs, including the kidneys. An over-exposure to metals, solvents and certain antibiotics and medication can also lead to this condition. An infection in the kidneys may cause them to shut down.

Obstructions in the urinary tract or renal artery can start acute kidney failure. Tumors, kidney stones or an enlarged prostate can block the flow of urine in the urinary tract. A blockage in the renal artery can cut off the supply of oxygen to the kidneys. Oxygen is necessary for kidney function. When the kidneys are starved for oxygen, a condition called Acute Tubular Necrosis (ATN) sets in.

Shock or trauma to the body can lead to low blood pressure. Sometimes the stress of surgery on the body can lower blood pressure to dangerous levels. Extremely low blood pressure means there is a decrease in blood flow. Kidneys will not receive oxygen or filter blood as efficiently as before. 

What symptoms should I look for?

The most obvious symptom of acute kidney failure is a decrease of urine. This symptom occurs in 70% of cases. Patients who fall into this category are said to be oliguric. Their urine output is less than 16 ounces a day.

When urine output is low, fluid retention will occur. Excess fluid will cause swelling in the legs, feet and ankles.  Because wastes are not being removed from the body, patients will feel ill. In addition, many patients report:

• feeling nauseated
• vomiting
• feeling drowsy
• having difficulty paying attention
• experiencing numbness or decreased sensation in the hands and feet

Doctors can easily diagnose acute kidney failure with blood and urine tests. Increased amounts of creatinine and urea nitrogen in the blood are causes for concern.

How is acute kidney failure treated?

Doctors will first treat any reversible illnesses that caused the kidney failure. Infections can be treated with medication. Blockages such as tumors or kidney stones may need to be removed. 

Since treating the causes of the acute kidney failure takes time, the body will be unable to remove the waste from the bloodstream. The patient will undergo dialysis. Dialysis will remove the toxins from the bloodstream and help the patient feel better. 

Sometimes patients develop high levels of potassium in their blood as a result of acute kidney failure. This is condition is called hyperkalemia. Doctors can prescribe medication to bring an elevated potassium level under control.   

In order to help keep the wastes and electrolytes at acceptable levels, patients may be placed on a special diet that is low in protein, salt and potassium. Their fluid intake may also be restricted. 

Can I prevent acute kidney failure?

Staying healthy is the best way to prevent acute kidney failure. If you are going to be hospitalized for surgery or an illness, be aware of the risks and complications of any procedure you may undergo. Immediately report any changes in your urine output. And, as always, follow any instructions your doctors and nurses give you.

Keeping an open channel of communication with your health care team can help you get the treatment you need if acute kidney failure occurs.