What is Acute Kidney Injury (AKI)?
AKI is a syndrome that results in a sudden decrease in kidney function or kidney damage within a few hours or few days.
AKI is common in patients who are in the hospital especially in the elderly and those in intensive care units (ICU). AKI causes a build-up of waste products in your blood and makes it hard for your kidneys to keep a balance of fluid in your body. This can also affect other organs such as the brain, heart, and lungs.
AKI is found through simple blood and urine tests. AKI can lead to chronic kidney disease (CKD), or even kidney failure needing dialysis (end-stage kidney disease). It may also lead to heart disease or death. Even mild AKI or a seemingly "complete recovery" from AKI may have some short- and long-lasting health problems.
In the United States, AKI is one of the most serious and common health problems. It occurs in up to 1 in 5 patients in the hospital, and twice as often in a critical care setting.1-3 The best ways to lower the chances of having kidney damage and to save kidney function are to prevent AKI, or to find and treat AKI as early as possible.
Major causes of AKI include:
- Decreased blood flow to the kidneys. This can result from:
- Hypotension (low blood pressure) or shock
- Blood or fluid loss (e.g., bleeding, severe diarrhea)
- Heart attack, heart failure, and other conditions leading to decreased heart function
- Organ failure (e.g., heart, liver)
- Use of NSAIDs (e.g., ibuprofen, naproxen)
- Severe allergic (anaphylactic) reactions
- Major surgery
- Direct damage to the kidneys. Some examples include:
- Acute glomerulonephritis (inflammation and damage to the kidney glomerular membrane) such as lupus nephritis
- Acute interstitial nephritis (allergic reaction that can be caused by several drugs)
- Acute tubular necrosis (inflammation and damage to the kidney tubules from having low blood flow to the kidneys for a long time or toxic effects from drugs, heavy metals, or contrast dye used in imaging studies)
- Vasculitis (inflammation of blood vessels) such as Granulomatosis with Polyangiitis (rare blood vessel disease)
- Sepsis (total body response against infection which can cause poor organ function or poor blood flow)
- Thrombotic microangiopathy (damage to the cells that line the smallest blood vessels of the kidney)
- Multiple myeloma (plasma cell cancer)
- Scleroderma (connective tissue disease)
- Blockage of the urinary tract. Blockage can result from:
- Bladder, prostate, or cervical cancer
- Enlarged prostate
- Neurogenic bladder (problems with the nervous system that affect the bladder and urination)
- Kidney stones
- Blood clots in the urinary tract
Are you at risk?
Being older or African American/black increases your chance of getting AKI. There are also certain health conditions that increase your chance such as: conditions that require being in the hospital and ICU (e.g., severe sepsis), dehydration, chronic diseases such as heart disease, liver disease, lung disease, diabetes, peripheral artery disease (low blood flow to arms and legs due to narrowed arteries), kidney stones, cancer, and if you already have CKD.
How can you prevent AKI?
There are a number of steps that healthcare providers can take to lower your chance for getting AKI or problems related to AKI. If you have a higher chance of getting AKI, it is important that you know how well your kidneys are working: are my kidneys working as they should be for my age, gender, and race? Find out by asking your primary care provider to do two simple tests:
- A blood test for creatinine to find out how well your kidneys are working by estimating your glomerular filtration rate (eGFR)
- A urine test to find protein in the urine (proteinuria) which may show kidney damage
It is also important to make sure that all healthcare providers caring for you, particularly radiologists, anesthesiologists, and surgeons, know about your kidney health, or any other risk factors you may have for AKI. The kidneys clear certain medicines and contrast dye used in imaging studies. If your kidneys are not working normally, these drugs may not be a good choice for you as they may increase your chance for AKI. These drugs or imaging studies may be important for your health care, so you and your healthcare provider should decide what is best for you.
Here are other preventive measures:
- Stay well hydrated – drink water!
- Avoid long term use of drugs that are toxic to the kidneys such as NSAIDs (ibuprofen, naproxen) or herbal remedies
What are the effects of AKI?
- AKI causes a build-up of waste products in your blood and makes it hard for your kidneys to keep a balance of fluid in your body. This can affect other organs such as the brain, heart, and lungs which may lead to heart failure or resipratory failure (when not enough oxygen passes from the lungs to the blood).
- About 1 in 5 hospitalized patients get AKI. This number approximately doubles for patients in the ICU setting.1-4
- Severely ill patients with AKI who are in the hospital have the highest chance of death, up to 50%.1-4
- Approximately 1 in 10 patients who have AKI need dialysis:
- A significant number of those patients will die in the hospital and approximately 20% of survivors will continue to need dialysis after they are sent home from the hospital.4-6
- Among survivors needing dialysis after having AKI, some will need to stay on dialysis permanently.4-6
- About one third of patients who have AKI will develop CKD within 2 to 5 years of having AKI. This risk increases with more severe and repeated episodes of AKI.6-11
- Patients who live after having AKI have higher chances for stroke and heart disease (e.g., heart attack, heart failure).12,13
What should you do to protect your kidneys after an episode of AKI?
- If you are in the hospital for AKI, the medical team will test how well your kidneys work every day. It is important to talk with your healthcare team and make sure you understand your kidney health status and follow-up plan after you leave the hospital. You should follow-up with your primary care provider or kidney specialist within the next 6 to 12 weeks after you are sent home from the hospital. Tests that will tell whether or not your kidneys are better after AKI include serum (blood) creatinine, estimated glomerular filtration rate (eGFR), and the amount of protein in the urine. Learn more about these kidney tests.
- If you had AKI and still need dialysis, a kidney doctor will be in charge of your outpatient dialysis treatments. Your kidney doctor will continue to check if your kidney function is getting better. If your kidney function improves and you no longer need dialysis, you should still follow-up with a kidney doctor within 4 to 8 weeks after you stop dialysis treatment.
- After your first follow-up visit after having AKI, your doctor will tell you how often you should continue seeing a kidney specialist and testing your kidney function. This will be based on your kidney function and overall health.
- The kidneys clear several drugs, so your healthcare provider will review all your prescribed medications and over-the-counter products you are taking. Sometimes the doses of the medicines you usually take will be either increased or decreased based on changes in your kidney function. You must also stop or avoid all unnecessary medicines that could further damage your kidneys. These include NSAIDs.
- After having AKI, your chances are higher for other health problems (e.g., CKD, stroke, heart disease) or having AKI again in the future. The chances for CKD and kidney failure increase every time AKI occurs.
- To protect yourself you should:
- Follow up with your primary care provider or kidney doctor after having AKI to evaluate your kidney function recovery and your risk for post-AKI complications
- Discuss with your doctor if your prescribed medicines are right for your current kidney function
- Avoid using drugs that are toxic to the kidneys such as NSAIDs or herbal remedies or supplements
- Work with your healthcare team to identify modifiable risk factors and prevent recurrent episodes of AKI
If you would like more information about AKI, please contact us. Special thanks to Javier A. Neyra, M.D. for his help with this entry.
- Waikar SS, Liu KD, Chertow GM. Diagnosis, epidemiology and outcomes of acute kidney injury. Clinical journal of the American Society of Nephrology : CJASN. May 2008;3(3):844-861.
- Bellomo R, Kellum JA, Ronco C. Acute kidney injury. Lancet. Aug 25 2012;380(9843):756-766.
- Bagshaw SM, George C, Bellomo R. Early acute kidney injury and sepsis: a multicentre evaluation. Crit Care. 2008;12(2):R47.
- Cerda J, Liu KD, Cruz DN, et al. Promoting Kidney Function Recovery in Patients with AKI Requiring RRT. Clinical journal of the American Society of Nephrology : CJASN. Jul 2 2015.
- Chawla LS, Kimmel PL. Acute kidney injury and chronic kidney disease: an integrated clinical syndrome. Kidney international. Sep 2012;82(5):516-524.
- Heung M, Chawla LS. Acute kidney injury: gateway to chronic kidney disease. Nephron. Clinical practice. 2014;127(1-4):30-34.
- Thakar CV, Christianson A, Himmelfarb J, Leonard AC. Acute kidney injury episodes and chronic kidney disease risk in diabetes mellitus. Clinical journal of the American Society of Nephrology : CJASN. Nov 2011;6(11):2567-2572.
- Chawla LS, Amdur RL, Amodeo S, Kimmel PL, Palant CE. The severity of acute kidney injury predicts progression to chronic kidney disease. Kidney international. Jun 2011;79(12):1361-1369.
- Coca SG, Singanamala S, Parikh CR. Chronic kidney disease after acute kidney injury: a systematic review and meta-analysis. Kidney international. Mar 2012;81(5):442-448.
- Wald R, Quinn RR, Adhikari NK, et al. Risk of chronic dialysis and death following acute kidney injury. The American journal of medicine. Jun 2012;125(6):585-593.
- Lafrance JP, Miller DR. Acute kidney injury associates with increased long-term mortality. Journal of the American Society of Nephrology : JASN. Feb 2010;21(2):345-352.
- Wu VC, Wu CH, Huang TM, et al. Long-term risk of coronary events after AKI. Journal of the American Society of Nephrology : JASN. Mar 2014;25(3):595-605.
- Wu VC, Wu PC, Wu CH, et al. The impact of acute kidney injury on the long-term risk of stroke. Journal of the American Heart Association. Aug 2014;3(4).
© 2015 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.