What Is Acute Kidney Failure?
Acute kidney failure is when your kidneys stop working suddenly. Doctors sometimes call it acute renal failure. It can happen over just a few hours or days.
Acute kidney failure isn’t always permanent. If you get treatment right away -- and if you don’t have other serious health problems -- your kidneys can go back to working normally.
The main job of your kidneys is to filter waste out of your blood. They also remove extra fluid from your blood (this becomes urine) and control blood pressure. Kidneys help make red blood cells. They regulate electrolytes (a type of nutrient) and activate vitamin D, too.
Kidneys don’t work well when they’re damaged. This could happen because of another health condition, like diabetes. A decrease in kidney function that happens over a longer period of time is called chronic kidney disease (CKD).
Acute Kidney Failure Symptoms
You may not have any symptoms of acute kidney failure. Your doctor may discover you have this condition while doing lab tests for another reason.
If you do have symptoms, they’ll depend on how bad your loss of kidney function is, how quickly you lose kidney function, and the reasons for your kidney failure. Symptoms may include:
- Peeing less than normal
- Swelling in your legs, ankles, and feet (caused by your body holding on to fluid)
- Feeling drowsy or very tired
- Shortness of breath
- Joint pain, swelling
- Loss of appetite
- Throwing up or feeling like you’re going to
- Chest pain or pressure
- Muscle twitching
- Seizures or coma (in severe cases)
- Stomach and back pain
Acute Kidney Failure Causes
There are three main reasons your kidneys fail all of a sudden:
Something is changing the way blood flows through to your kidneys. It could be because of:
- An infection
- Liver failure
- Medications (aspirin, ibuprofen, naproxen, or COX-2 inhibitors like Celebrex)
- Blood pressure medications
- Heart failure
- Serious burns or dehydration
- Blood or fluid loss
- You have a condition that’s blocking urine from leaving your kidneys. This could mean:
- Bladder, cervical, colon, or prostate cancer
- Blood clots in your urinary tract
- An enlarged prostate
- Kidney stones
- Nerve damage in your bladder
- Something has directly damaged your kidneys, like:
- Blood clots
- Cholesterol deposits
- Medications that can directly damage kidneys, including NSAIDs like ibuprofen and naproxen, chemotherapy, and antibiotics
- Glomerulonephritis (inflamed kidney filters; this can be caused by an infection, autoimmune disease (like lupus, vasculitis, and scleroderma), multiple myeloma, chemotherapy drugs, antibiotics, or other toxins)
Acute Kidney Failure Risk Factors
Most of the time, kidney failure happens along with another medical condition or event. If you fall into any of the following categories, you may have a greater chance of acute kidney failure:
- You’ve been hospitalized for a long time, especially in intensive care.
- You have diabetes.
- You’re elderly.
- You have coronary artery disease.
- You have heart failure or high blood pressure.
- You have chronic kidney or liver disease.
Acute Kidney Failure Diagnosis
Your doctor will start with a physical exam. Then, they’ll order tests of your blood, urine, and kidneys.
Blood tests. These measure substances in your blood.
- Creatinine is a waste product in your blood that’s made by muscle activity. Normally, it’s removed from your blood by your kidneys. But if your kidneys stop working, your creatinine level rises.
- Urea nitrogen is another waste product in your blood. It’s created when protein from the foods is broken down. Like creatinine, your kidneys remove this from your blood. When your kidneys stop working, your urea nitrogen levels rise.
- Potassium is an electrolyte found in your blood that balances water levels in your bloodstream. Kidney disease can cause either high or low potassium levels.
- Sodium is an electrolyte that helps with fluid balance in your body. High sodium levels can mean that your kidneys aren’t working properly because your body can’t get rid of the right amount of sodium.
Urine tests. Your doctor will check your pee for blood and protein. They’ll also look for certain electrolytes. The results help your doctor understand what’s causing your kidney failure.
Kidney biopsy (renal biopsy) is a procedure where the doctor pushes a thin needle through your skin and takes a small piece of your kidney to look at under a microscope. It can show if there is any damage or disease in your kidney, and frequently what the cause is. This is typically done only in cases where it is unclear what is causing the kidney failure.
Imaging tests. Some tests, like ultrasonography or a CT scan, can show whether your kidneys are enlarged or there’s a blockage in your urine flow. They can also tell your doctor if there is any problem with arteries or veins going in and out of your kidneys. An MRI can show this, too.
Kidney Failure Treatment
Often, treatment for acute kidney failure, especially if severe, requires hospitalization. If there aren’t any other problems, the kidneys may heal themselves.
In most other cases, acute kidney failure can be treated if it’s caught early. It may involve changes to your diet, the use of medications, intravenous fluids, relief of any obstruction that is blocking kidneys, or even dialysis.
- Diet. Your doctor will limit the amount of salt and potassium you get until your kidneys heal. That’s because both of these substances are removed from your body through your kidneys. Changing how and what you eat won’t reverse acute kidney failure. But your doctor may change your diet while they treat the conditions that caused it. This may mean treating a health problem like heart failure, taking you off certain medications, or giving you fluids through an IV if you’re dehydrated. If your doctor has put you on a low potassium diet, you’ll need to cut back on high-potassium foods like bananas, spinach, oranges, potatoes, and tomatoes. On the other hand, you can eat more low-potassium foods like apples, strawberries, grapes, and cauliflower.
- Medications. Your doctor may prescribe medicines that regulate the amount of phosphorus and potassium in your blood. When your kidneys fail, they can’t remove these substances from your body. Medications won’t help your kidneys, but they may reduce some of the problems kidney failure causes.
- Dialysis. If your kidney damage is severe enough, you may require hemodialysis until your kidneys can heal. Dialysis does not help kidneys heal but takes over the work of kidneys until they do. If your kidneys don't heal, dialysis could be long-term.
Acute Kidney Failure Complications
Acute kidney failure can sometimes cause complications. These include:
- Fluid buildup. Acute kidney failure can sometimes cause a buildup of fluid in your body. If fluid builds up in your lungs, this can cause shortness of breath.
- Chest pain. If the lining that covers your heart becomes inflamed, you may have chest pain.
- Acidic blood (metabolic acidosis). If your blood has too much acid due to acute kidney failure, you can end up with nausea, vomiting, drowsiness, and breathlessness.
- Muscle weakness. When your body's fluids and electrolytes are out of balance, you can get muscle weakness. In serious cases, this can lead to paralysis and heart rhythm problems.
- Permanent kidney damage. Acute kidney failure can become chronic and your kidneys will stop working almost entirely or completely. This is called end-stage renal disease. If this happens, you will need to go on permanent dialysis (to filter your blood and remove toxins) or get a kidney transplant.
- Death. Acute kidney failure can lead to loss of kidney function that is so bad, it can cause death.
Acute Kidney Failure Prevention
You can reduce your risk of getting acute kidney failure by practicing some healthy habits.
- Be careful when taking over-the-counter (OTC) pain medications. Whether you are taking NSAID medications like aspirin, ibuprofen, and naproxen or other types of OTC pain medications like acetaminophen, it’s important to read and follow the recommended dosing instructions on the package. If you take too much of these meds, you could increase your chances of getting acute kidney failure.
- Follow your doctor’s advice. If you have a higher risk of getting acute kidney failure because of pre-existing kidney disease or other conditions, make sure to follow your doctor's advice for treating and managing your condition.
- Keep a healthy lifestyle. Exercise, eating right, and drinking little or no alcohol can go a long way to preventing acute kidney failure.