Acute Kidney Injury: What You Need to Know


Acute kidney injury (AKI) is a disease that will take the lives of two million people worldwide this year. (1) It’s a disease that has no cure. One in three adults in the United States (2) and 50% of intensive care unit (ICU) patients (3) are at risk for getting kidney disease.

Unfortunately, acute kidney injury is often not diagnosed until permanent kidney damage has already been done. By the time a patient experiences symptoms, the damage can be irreversible. 

Because adults over 60 are at higher risk for kidney disease, it’s important to know the symptoms of acute kidney injury and steps you can take to prevent it.

What is Acute Kidney Injury?

Acute kidney injury (formerly called acute kidney failure or acute renal failure) occurs when your kidneys are temporarily unable to do their job of filtering waste from your blood. This causes that waste to build up in your body, resulting in chemical imbalances.

Acute kidney injury (AKI) develops quickly—usually within 48 hours. (4) It most often happens while patients are in the hospital for other conditions, such as diabetes or hypertension. AKI is a serious condition that can cause life-threatening complications if symptoms aren’t treated immediately. (5)

If AKI is discovered and treated quickly, it is sometimes reversible. However, it can lead to permanent kidney damage, or chronic kidney disease (CKD). CKD can result in kidney failure, also called end-stage renal disease (ESRD). (4) It can also cause damage to your heart, lungs, and brain. (6)   

What is the Difference Between Acute Kidney Failure and Chronic Kidney Disease? (7)

Most cases of acute kidney injury are discovered through routine blood tests while the patient is in the hospital for other conditions. 

If your doctor suspects AKI, he may then order a kidney ultrasound to determine whether your kidney condition is acute (AKI) or chronic (chronic kidney disease, or CKD).

Your doctor will also consider the presence or absence of symptoms to determine whether your kidney disease is acute or chronic. AKI is most often caused by a specific event, such as dehydration, medication, or blood loss from surgery. These events cause significant and sudden symptoms.

CKD is usually caused by long-term kidney damage by conditions such as diabetes or high blood pressure. Patients with CKD often have no symptoms at all until the disease is in its advanced stages.

Causes of Acute Kidney Injury

Anyone can get AKI, but it’s most common in people who are already hospitalized for other illnesses and critically ill patients who are in an intensive care unit (ICU). (8)

There are three categories of kidney injury. AKI can be brought on by medication, a sudden illness, or a toxin that causes one of the following: (9)(6)

  • Decreased blood flow to the kidneys. There are many events that can cause this. They include a severe drop in blood pressure, heart attack, blood loss during surgery, severe burns with fluid loss through the skin, or hemorrhage (massive bleeding).
  • Direct injury to the kidneys. Again, there are many potential causes for kidney injury, including certain medications, blood clots in the urinary tract, inflammation in the kidneys, toxic chemicals, procedures such as angiograms that use x-ray guidance, contrast dye used for CT scans, drug and alcohol abuse, and sepsis (a life-threatening inflammatory reaction to severe infection).
  • Blockage of the urinary tract. This can happen because of an obstruction outside the kidney, such as kidney stones, blood clot, bladder tumor, or an enlarged prostate in men. 

Risk Factors of Acute Kidney Injury

As above, people over the age of 60 have a higher risk of AKI. That risk is made higher still by other conditions that older adults can often have. These can include:  (4)(2)(10)

  • A pre-existing kidney condition.
  • High blood pressure.
  • People with diabetes are almost four times more likely to be hospitalized for AKI than individuals without diabetes.
  • Other chronic conditions, such as heart disease or liver disease.
  • Cardiovascular disease.
  • Peripheral artery disease.
  • A family history of kidney disease.
  • Being African-American, Native American, Asian, or Hispanic.

Symptoms of Acute Kidney Injury

Symptoms of AKI can vary based on the cause of your injury. Common symptoms include: (9) (7)

  • Decreased urine output.
  • High blood pressure.
  • Edema (swelling) from salt or fluid excess.
  • Nausea and vomiting.
  • Chest pain or pressure.
  • Pain in the side or lower back (flank pain).
  • Blood in the urine.
  • Muscle cramps.

If AKI is left untreated, it can cause damage to the heart and lungs, changes in behavior, seizures, or coma.

How is Acute Kidney Failure Diagnosed?

As above, AKI is usually diagnosed when a patient is in the hospital for another reason. When your provider notes abnormalities in your routine blood tests, he or she may order any of the following tests: (6)

  • Measuring urine output. The amount of urine you pass each day can be an important indicator of the reason for your AKI symptoms.
  • Urine tests. A urinalysis will often show signs of kidney failure.
  • Blood tests. Your provider will check your blood for BUN and creatinine levels as well as other electrolytes, such as phosphorous and potassium.
  • GFR: Your providers will use your blood tests to calculate your glomerular filtration rate (GFR). This will allow them to estimate the decrease in your kidney function.
  • Imaging tests.  Your providers may order an ultrasound to look for kidney abnormalities.
  • Kidney biopsy. In some cases, your doctor will do a biopsy, where a sample of a kidney will be removed with a small needle and sent for lab testing.

Treatment for Acute Kidney Injury

While You’re in the Hospital (4)(9)

Treatment for AKI is centered on first treating the cause of the kidney injury (hypertension, diabetes, kidney stone, etc.) Most people need hospitalization for treatment and recovery.

You will likely need other treatment as well to treat the kidney damage itself. These can include:

  • Medications to correct the chemical balance of your blood. This could mean adjusting your levels of sodium and potassium, for example.
  • Treatment to balance the fluid levels in your body. This involves either IV fluids (to replenish fluid) or diuretic medication (to remove excess fluid).
  • If these treatments aren’t successful, you may need temporary hemodialysis to do the work of your kidneys until they have recovered. Dialysis is a procedure where a machine pumps blood through an artificial kidney (dialyzer). The dialyzer filters out the waste, then returns the blood to your body.

When You’re Discharged (4)

When you’re discharged from the hospital, your providers may order a kidney-safe diet while you recover. They may arrange a dietitian visit to help with this. They may also adjust your regular medications.

Medications for Acute Kidney Injury

There are no drugs that have been shown to be effective for acute kidney injury progression or recovery. (1) In fact, your doctor may even hold some of your medications temporarily, particularly while you’re in the hospital.

Potential Complications of Acute Kidney Injury (6)(11)(12)(13)(14)

Fluid buildup. AKI can lead to pulmonary edema, a buildup of fluid in your lungs that can cause shortness of breath.

Chest pain. The pericardium (or outer lining of the heart) may become inflamed. You may experience chest pain.

Muscle weakness. This can occur as a result of your electrolytes—the chemistry of your blood—being out of balance.

Infection. Infections are reported to occur in up to 33% of AKI patients. They are most likely to affect your lungs or urinary tract. Infections are the number one cause of related illness and death in AKI patients.

Permanent kidney disease. Patients with acute kidney failure are at high risk of developing CKD and permanent loss of kidney function (end-stage renal disease). People with ESRD need either lifelong dialysis or a kidney transplant to survive.

Injury to other organs. AKI can cause damage to your heart, lungs, liver, and brain.  

Higher risk of repeat AKI or other major illness. AKI increases your risk of having AKI again. It can also increase your risk of stroke or heart disease.

Prevention of Acute Kidney Injury

Acute kidney injury can be a serious condition, particularly for older adults. Because there are often no symptoms until kidney damage has already been done, you should know the symptoms to be watchful for and the steps you can take now to prevent AKI.

As you age, your kidney function reduces naturally, which makes you more sensitive to nephrotoxins—substances that are damaging to the kidneys, such as certain medications and imaging dyes. Work with your providers to find medications for your chronic conditions that pose the least risk to your kidneys.

Prevention of Acute Kidney Injury (15)

Because AKI happens suddenly, it’s hard to see it coming. But there are things you can do now to help prevent it. Follow these general rules to keep your kidneys as healthy as possible:

  • Work with your providers to manage chronic medications, particularly if you have high blood pressure. For the most part, blood pressure medications will help to protect your kidneys from damage. However, in certain cases, such as if you have the flu or diarrhea, they may put you at risk for AKI.
  • Keep a list of all of your medicines and supplements. Take the list with you to every appointment to be sure your provider’s list is up to date and that they know everything you’re taking.
  • Fill all of your prescriptions at one drug store or pharmacy chain. This will allow your pharmacist to monitor the drugs you are taking for harmful interactions.
  • If you are diabetic, be sure that you’re following all of your providers’ lifestyle advice. Remember that having diabetes is one of the largest risk factors for AKI and CKD.
  • Be careful with over-the-counter pain medications. If you take nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen, never take more than the package recommends. Taking too much of these medicines can cause AKI.
  • Avoid dehydration, especially if you take blood pressure medication. Symptoms to watch for are extreme thirst, dry skin, lightheadedness, rapid heartbeat, decreased urine output, dark yellow urine, lack of energy, rapid breathing, sleepiness, confusion, and irritability.
  • Live a healthy life. One of the best prevention measures you can take is to boost your immunity with a healthy diet and regular exercise.

Plan Ahead for Illness (15)

We all get sick from time to time. Preparing an action plan now will help lower your risk of AKI during those times.

Following are questions to ask your doctor and/or pharmacist so you will know what to do if you should get the flu, diarrhea, fever, or nausea and vomiting that can cause dehydration.

  • If I get sick, should I stop some of my medications?
  • If I need to stop medications while I’m ill, when can I restart them?
  • What can I do for a headache or other pain if I can’t take NSAIDs?
  • What can I take for a fever?
  • If I have vomiting or diarrhea, do I need to make changes to my blood pressure medication?

Because AKI comes on suddenly and requires immediate treatment, having a prevention plan can mean the difference between recovering from acute kidney injury and sustaining permanent kidney damage.

Prognosis for Acute Kidney Injury (16)

Because AKI is an unpredictable disease, the prognosis of patients who have it can vary widely. Your individual recovery will depend on the cause of your AKI, any complications you may have had, and how well they were controlled.

Unfortunately, AKI does have a high rate of permanent kidney dysfunction and even death. However, if the cause of your kidney injury wasn’t damage to the kidneys themselves, it is possible to make a full recovery.

It’s important to keep in mind that no matter what the cause, if acute kidney injury is not treated, it will almost certainly be fatal. It’s critical that you call your doctor at the first sign of kidney problems.

Early diagnosis and treatment are the keys to recovering from acute kidney injury.


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