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Kidney failure, also known as end-stage kidney disease, is a medical condition in which the
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...
s can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may resolve; and
chronic kidney failure Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, v ...
, which develops slowly and can often be irreversible. Symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications of acute and chronic failure include
uremia Uremia is the term for high levels of urea in the blood. Urea is one of the primary components of urine. It can be defined as an excess of amino acid and protein metabolism end products, such as urea and creatinine, in the blood that would be no ...
, high blood potassium, and
volume overload Volume overload refers to the state of one of the chambers of the heart in which too large a volume of blood exists within it for it to function efficiently. Ventricular volume overload is approximately equivalent to an excessively high preload ...
. Complications of chronic failure also include heart disease, high blood pressure, and anemia. Causes of acute kidney failure include low blood pressure, blockage of the urinary tract, certain medications, muscle breakdown, and hemolytic uremic syndrome. Causes of chronic kidney failure include diabetes, high blood pressure, nephrotic syndrome, and polycystic kidney disease. Diagnosis of acute failure is often based on a combination of factors such as decreased urine production or increased serum creatinine. Diagnosis of chronic failure is based on a glomerular filtration rate (GFR) of less than 15 or the need for
renal replacement therapy Renal replacement therapy (RRT) is therapy that replaces the normal blood-filtering function of the kidneys. It is used when the kidneys are not working well, which is called kidney failure and includes acute kidney injury and chronic kidney ...
. It is also equivalent to stage 5 chronic kidney disease. Treatment of acute failure depends on the underlying cause. Treatment of chronic failure may include hemodialysis, peritoneal dialysis, or a
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplant ...
. Hemodialysis uses a machine to filter the blood outside the body. In peritoneal dialysis specific fluid is placed into the abdominal cavity and then drained, with this process being repeated multiple times per day. Kidney transplantation involves surgically placing a kidney from someone else and then taking
immunosuppressant Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are drugs that inhibit or prevent activity of the immune system. Classification Immunosuppressive drugs can be classified in ...
medication to prevent rejection. Other recommended measures from chronic disease include staying active and specific dietary changes. 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 recent PCORI-funded study of patients with kidney failure receiving outpatient hemodialysis found similar effectiveness between nonpharmacological and pharmacological treatments for depression. In the United States acute failure affects about 3 per 1,000 people a year. Chronic failure affects about 1 in 1,000 people with 3 per 10,000 people newly developing the condition each year. Acute failure is often reversible while chronic failure often is not. With appropriate treatment many with chronic disease can continue working.


Classification

Kidney failure can be divided into two categories: acute kidney failure or
chronic kidney failure Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, v ...
. The type of renal failure is differentiated by the trend in the serum creatinine; other factors that may help differentiate acute kidney failure from chronic kidney failure include anemia and the kidney size on sonography as chronic kidney disease generally leads to anemia and small kidney size.


Acute kidney failure

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...
production, quantified as less than 400 mL per day in adults, less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants); and fluid and electrolyte imbalance. AKI can result from a variety of causes, generally classified as ''prerenal'', ''intrinsic'', and ''postrenal''. Many people diagnosed with paraquat intoxication experience AKI, sometimes requiring hemodialysis. The underlying cause must be identified and treated to arrest the progress, and dialysis may be necessary to bridge the time gap required for treating these fundamental causes.


Chronic kidney failure

Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms. CKD can be the long term consequence of irreversible acute disease or part of a disease progression.


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 serum creatinine. Like AKI, AoCRF can be difficult to distinguish from chronic kidney disease if the person has not been monitored by a physician and no baseline (i.e., past) blood work is available for comparison.


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 called azotemia. Very low levels of azotaemia 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 termed uraemia. Symptoms of kidney failure include the following: * High levels of urea in the blood, which can result in: ** Vomiting or diarrhea (or both) that may lead to dehydration ** Nausea ** Weight loss ** Nocturnal urination ( nocturia) ** More frequent urination, or in greater amounts than usual, with pale urine ** Less frequent urination, or in smaller amounts than usual, with dark coloured urine ** Blood in the urine ** Pressure, or difficulty urinating ** Unusual amounts of urination, usually in large quantities * A buildup of phosphates in the blood that diseased kidneys cannot filter out may cause: ** Itching ** Bone damage **
Nonunion Nonunion is permanent failure of healing following a broken bone unless intervention (such as surgery) is performed. A fracture with nonunion generally forms a structural resemblance to a fibrous joint, and is therefore often called a "false j ...
in broken bones ** Muscle cramps (caused by low levels of calcium which can be associated with hyperphosphatemia) * A buildup of
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
in the blood that diseased kidneys cannot filter out (called
hyperkalemia Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occa ...
) may cause: ** Abnormal heart rhythms ** Muscle paralysis * 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 hormone erythropoietin that stimulates the bone marrow to make 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 less
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythroc ...
, a condition known as anemia. This can result in: ** Feeling tired or weak ** Memory problems ** Difficulty concentrating **
Dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
** Low blood pressure * 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, 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 **
Difficulty sleeping Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...
** Darkening of the skin ** Excess protein in the blood ** With high doses of penicillin, people with kidney failure may experience
seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...


Causes


Acute kidney injury

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. Drug overdoses, accidental or from chemical overloads of drugs such as antibiotics or chemotherapy, along with bee stings 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. Among the accidental causes of renal failure is the crush syndrome, when large amounts of toxins are suddenly released in the blood circulation after a long compressed
limb Limb may refer to: Science and technology * Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, ...
is suddenly relieved from the pressure obstructing the blood flow through its tissues, causing ischemia. The resulting overload can lead to the clogging and the destruction of the kidneys. It is a reperfusion 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 – notably myoglobin,
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
, and
phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
– that are the products of rhabdomyolysis (the breakdown of skeletal muscle damaged by ischemic conditions). The specific action on the
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...
s is not fully understood, but may be due in part to nephrotoxic metabolites of myoglobin.


Chronic kidney failure

Chronic kidney failure has numerous causes. The most common causes of chronic failure are diabetes mellitus and long-term, uncontrolled hypertension. 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. Other genetic illnesses cause kidney failure, as well. Overuse of common drugs such as ibuprofen, and acetaminophen (paracetamol) can also cause chronic kidney failure. Some infectious disease agents, such as hantavirus, can attack the kidneys, causing kidney failure.


Genetic predisposition

The '' APOL1'' gene has been proposed as a major genetic risk locus for a spectrum of nondiabetic renal failure in individuals of African origin, these include HIV-associated nephropathy (HIVAN), primary nonmonogenic forms of focal segmental glomerulosclerosis, and hypertension affiliated chronic kidney disease not attributed to other etiologies. Two western African variants in APOL1 have been shown to be associated with end stage kidney disease in African Americans and Hispanic Americans.


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, or glomerular 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) or
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplant ...
whenever feasible. ;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.
The National Kidney Foundation The National Kidney Foundation, Inc. (NKF) is a voluntary health organization in the United States, headquartered in New York City, with over 30 local offices across the country. Its mission is to prevent kidney and urinary tract diseases, impr ...
offers an easy to use on-line GFR calculator for anyone who is interested in knowing their glomerular filtration rate. (A serum creatinine level, a simple blood test, is needed to use the calculator.)


Use of the term ''uremia''

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. The term ''
uremia Uremia is the term for high levels of urea in the blood. Urea is one of the primary components of urine. It can be defined as an excess of amino acid and protein metabolism end products, such as urea and creatinine, in the blood that would be no ...
'' is now used for the illness accompanying kidney failure.


Complications

Those with end stage renal failure who undergo haemodialysis have higher risk of spontaneous intra-abdominal bleeding than the general population (21.2%) and non-occlusive mesenteric ischemia (18.1%). Meanwhile, those undergoing peritoneal dialysis have a higher chance of developing peritonitis and gastrointestinal perforation. However, the rate of acute pancreatitis does not differ from the general population.


Treatment

The treatment of acute kidney injury depends on the cause. The treatment of chronic kidney failure may include renal replacement therapy: hemodialysis, peritoneal dialysis, or
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplant ...
.


Diet

In non-diabetics and people with type 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 with type 2 diabetes. A whole food, plant-based diet may help some people with kidney disease. A high protein diet from either animal or plant sources appears to have negative effects on kidney function at least in the short term.


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. Other methods of reducing disease progression include minimizing exposure to nephrotoxins such as NSAIDs and intravenous contrast.


References


External links

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