Acute: 3 per 1,000 per year[8] Chronic: 1 per 1,000 (US)[1]
Kidney failure, also known asrenal failure orend-stage renal disease (ESRD), is a medical condition in which thekidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels.[2] Kidney failure is classified as eitheracute kidney failure, which develops rapidly and may resolve; andchronic kidney failure, which develops slowly and can often be irreversible.[6] Symptoms may includeleg swelling, feeling tired,vomiting, loss of appetite, andconfusion.[2] Complications of acute and chronic failure includeuremia,hyperkalemia, andvolume overload.[3] Complications of chronic failure also includeheart disease,high blood pressure, andanaemia.[4][5]
Treatment of acute failure depends on the underlying cause.[7] Treatment of chronic failure may includehemodialysis,peritoneal dialysis, or akidney transplant.[2] Hemodialysis uses a machine to filter the blood outside the body.[2] In peritoneal dialysis specific fluid is placed into theabdominal cavity and then drained, with this process being repeated multiple times per day.[2] Kidney transplantation involves surgically placing a kidney from someone else and then takingimmunosuppressant medication to preventrejection.[2] Other recommended measures from chronic disease include staying active and specific dietary changes.[2] Depression is also common among patients with kidney failure, and is associated with poor outcomes including higher risk of kidney function decline, hospitalization, and death. A recentPCORI-funded study of patients with kidney failure receiving outpatient hemodialysis found similar effectiveness between nonpharmacological and pharmacological treatments for depression.[9]
In the United States, acute failure affects about 3 per 1,000 people a year.[8] Chronic failure affects about 1 in 1,000 people with 3 per 10,000 people newly developing the condition each year.[1][10] In Canada, the lifetime risk of kidney failure or end-stage renal disease (ESRD) was estimated to be 2.66% for men and 1.76% for women.[11] Acute failure is often reversible while chronic failure often is not.[6] With appropriate treatment many with chronic disease can continue working.[2]
Kidney failure can be divided into two categories:acute kidney failure orchronic kidney failure. The type of renal failure is differentiated by the trend in the serumcreatinine; other factors that may help differentiate acute kidney failure from chronic kidney failure includeanemia and the kidney size onsonography as chronic kidney disease generally leads to anemia and small kidney size.[citation needed]
Acute kidney injury (AKI), previously called acute renal failure (ARF),[12][13] is a rapidly progressive loss ofrenal function,[14] generally characterized byoliguria (decreasedurine production, quantified as less than 400 mL per day in adults,[15] less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants); andfluid and electrolyte imbalance. AKI can result from a variety of causes, generally classified asprerenal,intrinsic, andpostrenal. Many people diagnosed withparaquat intoxication experience AKI, sometimes requiringhemodialysis.[citation needed] The underlying cause must be identified and treated to arrest the progress, anddialysis may be necessary to bridge the time gap required for treating these fundamental causes.[citation needed]
Illustration of a kidney from a person with chronic renal failure
Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms.[16] CKD can be the long term consequence of irreversible acute disease or part of a disease progression.[citation needed] CKD is divided into 5 different stages (1–5) according to the estimated glomerular filtration rate (eGFR). In CKD1 eGFR is normal and in CKD5 eGFR has decreased to less than 15 ml/min.[17]
Acute-on-chronic kidney failure
Acute kidney injuries can be present on top of chronic kidney disease, a condition called acute-on-chronic kidney failure (AoCRF). The acute part of AoCRF may be reversible, and the goal of treatment, as with AKI, is to return the person to baseline kidney function, typically measured by serumcreatinine. Like AKI, AoCRF can be difficult to distinguish from chronic kidney disease if the person has not been monitored by aphysician and no baseline (i.e., past) blood work is available for comparison.[citation needed]
Signs and symptoms
Symptoms can vary from person to person. Someone in early stage kidney disease may not feel sick or notice symptoms as they occur. When the kidneys fail to filter properly, waste accumulates in the blood and the body, a condition calledazotemia. Very low levels of azotemia may produce few, if any, symptoms. If the disease progresses, symptoms become noticeable (if the failure is of sufficient degree to cause symptoms). Kidney failure accompanied by noticeable symptoms is termeduraemia.[18]
Symptoms of kidney failure include the following:[18][19][20][21]
High levels ofurea in the blood, which can result in:
Failure of kidneys to remove excess fluid may cause:
Swelling of the hands, legs, ankles, feet, or face
Shortness of breath due to extra fluid on the lungs (may also be caused by anemia)
Polycystic kidney disease, which causes large, fluid-filled cysts on the kidneys and sometimes the liver, can cause:
Pain in the back or side
Healthy kidneys produce the hormoneerythropoietin that stimulates thebone marrow tomake oxygen-carrying red blood cells. As the kidneys fail, they produce less erythropoietin, resulting in decreased production of red blood cells to replace the natural breakdown of old red blood cells. As a result, the blood carries lesshemoglobin, a condition known asanemia. This can result in:
Normally proteins are too large to pass through the kidneys. However they are able to pass through when the glomeruli are damaged. This does not cause symptoms until extensive kidney damage has occurred,[23] after which symptoms include:
Foamy or bubbly urine
Swelling in the hands, feet, abdomen, and face
Other symptoms include:
Appetite loss, which may include a bad taste in the mouth
Acute kidney injury (previously known as acute renal failure) – or AKI – usually occurs when the blood supply to the kidneys is suddenly interrupted or when the kidneys become overloaded with toxins. Causes of acute kidney injury include accidents, injuries, or complications from surgeries in which the kidneys are deprived of normal blood flow for extended periods of time. Heart-bypass surgery is an example of one such procedure.[citation needed]
Drug overdoses, accidental or from chemical overloads of drugs such as antibiotics or chemotherapy, along with bee stings[25] may also cause the onset of acute kidney injury. Unlike chronic kidney disease, however, the kidneys can often recover from acute kidney injury, allowing the person with AKI to resume a normal life. People with acute kidney injury require supportive treatment until their kidneys recover function, and they often remain at increased risk of developing future kidney failure.[26]
Among the accidental causes of renal failure is thecrush syndrome, when large amounts oftoxins are suddenly released in theblood circulation after a long compressedlimb is suddenly relieved from the pressure obstructing the blood flow through its tissues, causingischemia. The resulting overload can lead to the clogging and the destruction of the kidneys. It is areperfusion injury that appears after the release of the crushing pressure. The mechanism is believed to be the release into the bloodstream of muscle breakdown products – notablymyoglobin,potassium, andphosphorus – that are the products ofrhabdomyolysis (the breakdown of skeletal muscle damaged byischemic conditions). The specific action on thekidneys is not fully understood, but may be due in part tonephrotoxicmetabolites of myoglobin.[citation needed]
Chronic kidney failure has numerous causes. The most common causes of chronic failure arediabetes mellitus and long-term, uncontrolledhypertension.[27]Polycystic kidney disease is another well-known cause of chronic failure. The majority of people affected with polycystic kidney disease have a family history of the disease. Systemic lupus erythematosus (SLE) is also a known cause of chronic kidney failure. Other genetic illnesses cause kidney failure, as well.[citation needed]
Overuse of common drugs such asibuprofen, andacetaminophen (paracetamol) can also cause chronic kidney failure.[28]
Some infectious disease agents, such ashantavirus, can attack the kidneys, causing kidney failure.[29]
Genetic predisposition
TheAPOL1 gene has been proposed as a major genetic risk locus for a spectrum of nondiabetic renal failure in individuals of African origin, these includeHIV-associated nephropathy (HIVAN), primary nonmonogenic forms offocal segmental glomerulosclerosis, and hypertension affiliatedchronic kidney disease not attributed to other etiologies.[30] Two western African variants in APOL1 have been shown to be associated with end stage kidney disease in African Americans and Hispanic Americans.[31][32]
Diagnostic approach
Measurement for CKD
Stages of kidney failure
Chronic kidney failure is measured in five stages, which are calculated using the person's GFR, orglomerular filtration rate. Stage 1 CKD is mildly diminished renal function, with few overt symptoms. Stages 2 and 3 need increasing levels of supportive care from their medical providers to slow and treat their renal dysfunction. People with stage 4 and 5 kidney failure usually require preparation towards active treatment in order to survive.Stage 5 CKD is considered a severe illness and requires some form of renal replacement therapy (dialysis) orkidney transplant whenever feasible.[citation needed]
Glomerular filtration rate
A normal GFR varies according to many factors, including sex, age, body size and ethnic background. Renal professionals consider the glomerular filtration rate (GFR) to be the best overall index of kidney function.[33]The National Kidney Foundation offers an easy to use on-line GFR calculator[34] for anyone who is interested in knowing their glomerular filtration rate. (A serumcreatinine level, a simple blood test, is needed to use the calculator.)
Use of the termuremia
Before the advancement of modern medicine, renal failure was often referred to as uremic poisoning. Uremia was the term for the contamination of the blood with urea. It is the presence of an excessive amount of urea in blood. Starting around 1847, this included reduced urine output, which was thought to be caused by the urine mixing with the blood instead of being voided through the urethra.[citation needed] The termuremia is now used for the illness accompanying kidney failure.[35]
Renal failure index
Two other urinary indices, are thefractional sodium excretion (FENa) index and the renal failure index (RFI).[36] The renal failure index is equal to urine sodium times plasma creatinine divided by urinecreatinine.[36] A FENa score greater than 3% or a renal failure index (RFI) greater than 3 are helpful in confirming acute renal failure.[37]
In non-diabetics and people withtype 1 diabetes, a low protein diet is found to have a preventive effect on progression of chronic kidney disease. However, this effect does not apply to people withtype 2 diabetes.[39] A whole food,plant-based diet may help some people with kidney disease.[40] A high protein diet from either animal or plant sources appears to have negative effects on kidney function at least in the short term.[41]
Slowing progression
People who receive earlier referrals to a nephrology specialist, meaning a longer time before they must start dialysis, have a shorter initial hospitalization and reduced risk of death after the start of dialysis.[42] Other methods of reducing disease progression include minimizing exposure tonephrotoxins such asNSAIDs andintravenous contrast.[43]
^Mehrotra R, Cukor D, Unruh M, Rue T, Heagerty P, Cohen SD, et al. (March 2019). "Comparative Efficacy of Therapies for Treatment of Depression for Patients Undergoing Maintenance Hemodialysis: A Randomized Clinical Trial".Annals of Internal Medicine.170 (6):369–379.doi:10.7326/M18-2229.PMID30802897.S2CID67876948.
^"Acute kidney failure".A.D.A.M. Medical Encyclopedia. U.S. National Library of Medicine. 2012. Archived fromthe original on 17 January 2014. Retrieved1 January 2013.
^The PD Companion. Deerfield, Illinois: Baxter International Inc. 2008-05-01. pp. 14–15. 08/1046R. Archived fromthe original on 2010-06-25. Retrieved2010-07-12.
^National Kidney and Urologic Diseases Information Clearinghouse (2012)."The Kidneys and How They Work". National Institute of Diabetes and Digestive and Kidney Diseases. Archived fromthe original on 2 May 2015. Retrieved1 January 2013.
^Chauveau P, Combe C, Fouque D, Aparicio M (November 2013). "Vegetarianism: advantages and drawbacks in patients with chronic kidney diseases".Journal of Renal Nutrition.23 (6):399–405.doi:10.1053/j.jrn.2013.08.004.PMID24070587.
^Bernstein AM, Treyzon L, Li Z (April 2007). "Are high-protein, vegetable-based diets safe for kidney function? A review of the literature".Journal of the American Dietetic Association.107 (4):644–50.doi:10.1016/j.jada.2007.01.002.PMID17383270.S2CID39551628.
^Smart NA, Dieberg G, Ladhani M, Titus T (June 2014). "Early referral to specialist nephrology services for preventing the progression to end-stage kidney disease".The Cochrane Database of Systematic Reviews (6): CD007333.doi:10.1002/14651858.CD007333.pub2.PMID24938824.
