acute kidney injury?
Acute kidney injury (AKI) is a sudden decline in kidney function caused by one or more of the following:
- Lack of blood flow to the kidneys
- Direct damage to the kidneys
- Blockage of urine from the kidneys
AKI happens quickly, usually within a few hours or days. When it happens, your kidneys lose the ability to filter waste and extra fluid from your body. As a result, toxins build up, potentially causing great harm to other organs and body systems. Early detection and treatment are very important to (1) promptly identify reversible conditions, such as a blockage causing urine to back up into the kidneys, and (2) prevent serious problems.
Left untreated, AKI can lead to many serious conditions, such as:
- Cardiovascular disease (heart attack, angina, coronary heart disease, stroke, pericarditis, hypertension)
- Edema (pulmonary, extremities)
- Neurologic (nerve damage, uremic encephalopathy)
- Weakened bones that can easily break
- Decreased ability to fight off infections
- Anemia Uremia
- Metabolic acidosis
- Electrolyte imbalance
- Kidney failure
What are the symptoms of AKI?
As with chronic kidney disease (CKD), there may not be any signs or symptoms that show in the early stages of AKI. Anyone who is at increased risk should be tested immediately.
Warning signs may include any of the following:
- Decreased urine output
- Fluid retention
- Swelling in the arms or legs
- Fatigue or drowsiness
- Shortness of breath
- High blood pressure
- Irregular heartbeat
- Flank pain (pain in upper abdomen or back)
- Chest pain or pressure
- Seizures or coma, in severe cases
If you have any of these symptoms, ask your doctor to check your kidneys.
What causes AKI?
While AKI usually occurs in connection with another disease or condition, such as chronic kidney disease (CKD), diabetes, or heart disease, it can also occur in people with normally functioning kidneys. Everyone is at risk, but some are at increased risk.
You are at risk if you have a sudden decrease in blood flow to the kidneys. This can result from a number of causes including other illnesses; being anemic or dehydrated; overuse of aspirin, ibuprofen, or other medications that harm the kidneys; burns; circulatory shock; and trauma. In the U.S., AKI is very common among hospitalized patients, as it can result after cardiac or other major surgeries as well as exposure to sepsis. Approximately 45 percent of patients in the Intensive Care Unit (ICU) develop AKI.1
You are also at risk of AKI if you have a condition in or around your kidneys that causes damage to their filtering system, resulting in a sudden loss of kidney function. Some of these conditions are:
- Glomerulonephritis (inflammation of the filtering units of the kidneys)
- Acute tubular necrosis (damage to the tiny tube that recycles sodium and potassium)
- Acute interstitial nephritis (reduces the kidneys’ ability to filter properly)
- Vascular disease (can lead to blood clots in the arteries and veins near the kidneys)
- Vasculitis (an inflammation of the blood vessels)
- Lupus (an immune system disorder)
If you have a blockage in your urinary tract that forces urine to back up into the kidneys, you are at risk for AKI. Some conditions that may cause this include:
- Blood clots in the urinary tract
- Kidney stones
- Enlarged prostate
- Colon, prostate, bladder, or cervical cancer
How do I know if I have AKI?
AKI is detected through two simple tests:
- A blood test that measures the amount of creatinine (a waste product produced by muscle activity) in the blood. It indicates how well your kidneys are filtering this waste.
- A urine test that measures the amount of urine being produced. This indicates whether there is damage or an obstruction that is blocking urine flow.
Once AKI is identified, further tests will be done to determine the cause, which may be reversible or treatable. You will want to discuss the appropriate additional tests with your doctor. Examples of further testing may include:
- Physical exam to identify signs of congestive heart failure or infection
- Patient history to identify use of medications that damage the kidneys
- Blood urea nitrogen (BUN) test to tell how well your kidneys and liver are working
- Complete blood count (CBC)
- Blood test to measure electrolytes (minerals in the body), which need to be balanced to perform vital body functions
- Estimated glomerular filtration rate (eGFR) to measure kidney function
- Ultrasound to rule out obstruction
Treatment will focus on the underlying illness or injury as well as, the management of complications of AKI, such as dehydration, swelling, urinary obstruction, overload of potassium or calcium in your body, or problems with blood pressure. Your doctor will continue to monitor you by measuring the creatinine in your blood and your urine output. Even when your condition is under control, you should receive a follow-up evaluation within three months of the AKI episode and be monitored for the long term.
- All patients who are at risk for AKI should ask their doctor to check their kidneys.
- Make sure your doctor has a current list of all medicines you are taking, including over-the-counter drugs. You will want to avoid overuse of aspirin or ibuprofen, as they can cause harm to the kidneys.
- Drink water to stay well-hydrated.
Adopt and maintain healthy behaviors.
- Be physically active.
- Eat a healthy diet that is low in fat, salt, and sugar.*
- Avoid tobacco products.
Keep other health problems under control.
- If you have diabetes, keep your blood sugar in your target range.
- Keep your blood pressure in your target range.
- Keep your cholesterol and other lipids (fats) in your target range.
- If you have frequent bladder infections, take steps to prevent them and get treated quickly.
- Take medicines as prescribed.
- Get your yearly physical exam, and ask your doctor to check your kidneys.
*If you have AKI or CKD, you should meet with a dietitian who specializes in nutrition for kidney conditions.
1 Li PKT, Burdmann EA, and Mehta RL. Acute kidney injury: Global health alert. J Nephropathol 2(2):90-97. April 2013. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891141/.