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What is acute renal failure? Acute renal failure (also called acute kidney injury) means that your kidneys have suddenly stopped working. Your kidneys remove waste products and help balance water and salt and other minerals (electrolytes) in your blood. When your kidneys stop working, waste products, fluids, and electrolytes build up in your body. This can cause problems that can be deadly. What causes acute renal failure? What is prerenal acute renal failure? What is intrinsic acute renal failure? What is postrenal acute renal failure? What is another word or term for acute renal failure? Acute kidney injury Acute renal failure is known today as acute kidney injury (AKI). What does acute renal failure mean? It means that your kidneys have abruptly stopped working, usually within the course of two days. Also known as acute kidney failure or acute kidney injury (AKI), it is a very serious condition requiring immediate medical treatment. What is acute renal failure? Acute renal failure (also called acute kidney injury) means that your kidneys have suddenly stopped working. Your kidneys remove waste products and help balance water and salt and other minerals (electrolytes) in your blood. When your kidneys stop working, waste products, fluids, and electrolytes build up in your body. This can cause problems that can be deadly. What causes acute renal failure? Acute renal failure has three main causes: A sudden, serious drop in blood flow to the kidneys. Heavy blood loss, an injury, or a bad infection called sepsis can reduce blood flow to the kidneys. Not enough fluid in the body (dehydration) also can harm the kidneys. Damage from some medicines, poisons, or infections. Most people do not have any kidney problems from taking medicines. People who have serious, long-term health problems are more likely than other people to have a kidney problem from medicines. The medicines that can sometimes harm the kidneys include: Antibiotics, such as gentamicin and streptomycin. Pain medicines, such as aspirin and ibuprofen. Some blood pressure medicines, such as ACE inhibitors. The dyes used in some X-ray tests. A sudden blockage that stops urine from flowing out of the kidneys. Kidney stones, a tumor, an injury, or an enlarged prostate gland can cause a blockage. You have a greater chance of getting acute renal failure if: You are an older adult. You have a long-term health problem such as kidney or liver disease, diabetes, high blood pressure, heart failure, or obesity. You are already very ill and are in the hospital or intensive care (ICU). Heart surgery or belly surgery or a bone marrow transplant can make you more likely to have kidney failure. Causes and Risk Factors of Acute Renal Failure Prerenal AKI Symptoms Intrinsic AKI Symptoms Postrenal AKI Symptoms What are the causes of acute prerenal failure? Prerenal causes of acute kidney failure are those that directly or indirectly decrease blood flow to the kidneys. Common causes include: Severe dehydration Severe low blood pressure (hypotension) Heart failure Advanced liver disease Narrowing of the renal artery or veins (renal stenosis) What are the causes of acute intrinsic renal failure? Intrinsic causes of acute renal failure are those that occur within the kidney itself, affecting either the filters of the kidneys (glomeruli), kidney tubules, or the tissues between these structures (interstitium). The most common causes are: Glomerulonephritis Acute tubular necrosis (ATN) Acute interstitial nephritis (AIN) What are the causes of acute postrenal failure? Postrenal cause of acute renal failure are those occur downstream from the kidneys and are most often the result of a urinary tract obstruction. Common causes include: Bladder stones Kidney stones Benign prostatic hyperplasia (enlarged prostate) Obstructed urinary catheter Cancer of the ureters, prostate, or bladder How does heart failure cause acute renal failure? Blood flow to the kidneys can be affected by circulatory problems in any part of the body. When you have heart failure, your heart muscle may be unable to pump enough blood to supply your tissues and organs. This can lead to cardiorenal syndrome in which the failure of the heart can directly affect the kidneys (and vice versa). How does liver disease cause acute renal failure? Blood flow to the kidneys can be indirectly affected by liver cirrhosis and liver failure. When these conditions occur, there is a pooling of blood in the splanchnic circulation, which, in turn, decreases circulation to the kidneys. This can lead to type 1 hepatorenal syndrome, a life-threatening condition that ultimately requires a liver transplant. How does sepsis cause acute renal failure? Sepsis occurs when the immune system’s response to an infection causes damage to tissues. This can lead to multi-organ failure, including acute intrinsic kidney failure. Around 19% of people with moderate sepsis develop acute renal failure, increasing to 23% when sepsis is severe, and 51% with septic shock. How do drugs cause acute renal failure? Every drug you take passes through the kidneys to some degree. Some can cause damage to the glomeruli, tubules, or interstitium of a kidney, either over a period of time or when taken at high doses (especially in people with underlying kidney disease). Common culprits include: ACE inhibitors Angiotensin receptor blockers (ARBs) Antibiotics Contrast dyes Loop diuretics Nonsteroidal anti-inflammatory drugs (NSAIDs) Proton pump inhibitors (PPIs) Prerenal AKI Symptoms Acute kidney injury can occur for any number of reasons but is broadly classified as being either prerenal (caused by decreased blood flow to both kidneys), intrinsic (caused by damage to the kidneys), or postrenal (due most often to a urinary tract obstruction).2 While each will lead to the same outcome—the build-up of toxic waste in the body—the underlying impairment will carry its own set of symptoms, of which AKI would be considered a complication. The most common causes of prerenal causes of AKI (also known as prerenal azotemia) are severe dehydration, heart failure, and liver cirrhosis, all of which can impair blood flow to the kidneys. The underlying causes can often be differentiated by their symptoms. Examples of this include: Severe dehydration symptoms may include sunken eyes, dry skin, decreased skin elasticity, dry mouth and eyes, rapid heart rate (tachycardia), and dizziness or lightheadedness when standing or sitting up ( orthostatic hypotension). Heart failure symptoms may include bulging neck veins, cracking or rattling sounds in the lungs (pulmonary rales), tachycardia, heart palpitations, shortness of breath when lying down, abdominal swelling (ascites), and a persistent cough or wheezing with pink-tinged phlegm. Liver cirrhosis symptoms may include ascites, yellowing of the eyes and skin (jaundice), spider veins (spider angioma), sweet- or ammonia-smelling urine, and engorged veins on the surface of the abdomen radiating from the navel (caput medusae). Intrinsic AKI Symptoms The most common cause of intrinsic AKI is kidney damage related to such conditions as glomerulonephritis, acute tubular necrosis, and acute interstitial nephritis. Among some of the differentiating symptoms: Glomerulonephritis, the inflammation of blood vessels in the kidneys, may cause symptoms such as pink or bloody urine (hematuria), foamy urine from excess protein (proteinuria), and swelling of the face, hands, feet, and abdomen. Acute tubular necrosis (ATN), a condition in which kidney tissues begin to die from the lack of oxygen, can manifest with such symptoms as deep and persistent muscle pain, muscle spasms, a sensation of pins and needles (neuropathy), generalized swelling of the body, and confusion or delirium. Acute interstitial nephritis (AIN), the swelling of tissue in between the kidney tubules (often caused by a drug reaction or autoimmune disease), may be accompanied by fever, hematuria, generalized swelling of the body, vomiting, confusion, and a rash (if drug-related). Postrenal AKI Symptoms The most common cause of postrenal AKI is a urinary tract obstruction which can be caused by an enlarged prostate gland (benign prostatic hyperplasia), kidney stones, bladder stones, or cancer of the kidneys, bladder, or prostate. Benign prostatic hyperplasia (BPH) symptoms include dribbling after urination, excessive urination at night (nocturia), frequent urination, a sense of incomplete bladder clearance, persistent urge to urinate (urinary urgency), or weak urine flow. Kidney and bladder stone symptoms include an intense lower abdominal or flank pain, hematuria, cloudy urine, a burning sensation during urination (dysuria), difficulty urinating, and pain or discomfort in the testicles or penis in men. Cancer symptoms may include weight loss, hematuria, dysuria, urinary urgency, weak urinary flow, inability to urinate, lower back pain on one side, and bone pain. What are the symptoms? Symptoms of acute renal failure may include: Little or no urine when you urinate. Swelling, especially in your legs and feet. Not feeling like eating. Nausea and vomiting. Feeling confused, anxious and restless, or sleepy. Pain in the back just below the rib cage. This is called flank pain. Some people may not have any symptoms. How is acute renal failure diagnosed? Your doctor will ask about symptoms you may have, what medicines you take, and what tests you have had. Your symptoms can help point to the cause of your kidney problem. Blood and urine tests can check how well your kidneys are working. A chemistry screen can show if you have normal levels of sodium (salt), potassium, and calcium. You may also have an ultrasound. This imaging test lets your doctor see your kidneys. If you are already in the hospital, tests done for other problems also may find kidney failure. How is it treated? Your doctor or a kidney specialist (nephrologist) will try to treat the problem that is causing your kidneys to fail. At the same time, the doctor will try to: Stop wastes from building up in your body. You may have dialysis. This treatment uses a machine to do the work of your kidneys until they recover. It will help you feel better. Prevent other problems. You may take antibiotics to prevent or treat infections. You also may take other medicines to get rid of extra fluid and keep your body’s minerals in balance. You can help yourself heal by taking your medicines as your doctor tells you to. You also may need to follow a special diet to keep your kidneys from working too hard. You may need to limit sodium, potassium, and phosphorus. A dietitian can help you plan meals. Does acute renal failure cause lasting problems? About half the time, doctors can fix the problems that cause kidney failure in a few days or weeks. These people’s kidneys will work well enough for them to live normal lives. But other people may have permanent kidney damage that leads to chronic kidney disease. Older people and those who are very sick from other health problems may not get better. People who die usually do so because of the health problem that caused their kidneys to fail. What is a dialysis machine? A dialysis machine is a machine that cleans the blood of toxins when the kidneys are not working. The patient's blood enters the dialysis machine and goes through a special filter that works like the kidney to remove fluid and toxins from the blood. The use of the dialysis machine is termed hemodialysis. A patient undergoing hemodialysis must be connected to the hemodialysis machine by tubing that allows blood to flow to and from the dialysis machine. The tubing is connected to the patient by way of a dialysis shunt or catheter. When is a dialysis machine used? A dialysis machine is used when a patient's kidneys cannot effectively clean the blood. Does use of a dialysis machine hurt? The use of the dialysis machine does not hurt. How long is a dialysis machine used? The dialysis machine can be used for a short period of time or for a long period of time, depending on what is wrong with the kidneys. Are there any potential complications associated with use of a dialysis machine? The potential complications associated with the use of the dialysis machine are very uncommon and include bleeding and infection. During dialysis a patient's blood pressure may vary due to the fluid shifts. The common signs and symptoms of AKI may include:1 Decreased urine output Swelling of the legs, ankles, and feet (edema) Shortness of breath (dyspnea) Fatigue Loss of appetite Nausea and vomiting Irregular heartbeats (arrhythmia) Chest pain or pressure Easy or unusual bleeding (caused by low platelets) Confusion Seizures Coma Many of the characteristic symptoms of AKI are related to a condition known as uremic encephalopathy in which the accumulation of urea, creatinine, and other substances in the blood trigger disturbances in the brain, affecting not only bodily functions but mental processes, as well. Other symptoms are caused by imbalances in potassium or fluid levels which directly impact the heart, circulation, and blood pressure. What are the early signs and symptoms of acute renal failure? Acute renal failure develops rapidly, usually over the course of 48 hours. Early signs and symptoms include:3 Decreased urine output Swelling of the legs, ankles, and feet Fatigue and weakness Shortness of breath Nausea Irregular heartbeat What are the respiratory symptoms of acute renal failure? Dyspnea (shortness of breath) is the main respiratory symptom. Acute renal failure can cause the build-up of acid in the bloodstream, leading to fluid in the lungs and decreasing the amount of oxygen that enters the bloodstream. The lack of oxygen and increased carbon dioxide levels are what lead to shortness of breath.5 What are the possible complications of acute renal failure? Because the organs of the body are connected by the circulatory system, acute renal failure may not only affect the kidneys but other organs as well. Potential complications include: Hyperkalemia (excessive potassium in the blood) Metabolic acidosis Pericarditis (inflammation of the heart muscle) Pulmonary hemorrhage (bleeding) Pulmonary edema (swelling) Permanent kidney damage Are the symptoms of acute renal failure reversible? Oftentimes they are, depending on the cause, your general health, and how quickly and successfully the cause is treated. Certainly, acute renal failure, which occurs abruptly, is more likely to be reversible than chronic renal failure, which develops over time due to chronic kidney disease and other conditions.7 What are the symptoms of end-stage renal failure? End-stage renal disease (ESRD) occurs when the kidneys permanently fail to work. The symptoms are not unlike those for renal failure in general but may also include sleep problems, confusion, chest pain, vomiting, rash, weight loss, bone pain, and the inability to urinate. If you have ESRD, you will need dialysis or a kidney transplant to stay alive.7 When to Call Your Doctor Seek medical care if you experience the following symptoms: Increased water retention with swelling of the legs, face, or hands Decreased urinary output, oftentimes with very dark urine Sudden shortness of breath Sudden fatigue or marked changes in energy levels Easy bruising Persistent or recurrent dizziness and lightheadedness How is acute renal failure diagnosed? Acute renal failure is primarily diagnosed based on the amount of urine you produce over a period of time (urine volume) and the accumulation of a waste product called creatinine in your blood (serum creatinine) that your kidneys are usually able to eliminate. If you have acute renal failure, your urine volume will decrease and/or your serum creatinine will increase to abnormal levels.9 How is urine volume used to diagnose acute renal failure? If acute renal failure is suspected, your healthcare provider will collect and measure the amount of urine you produce over a six-hour period (called a urine volume test). Based on your weight, the practitioner can estimate the functional status of your kidneys. A normal urine output for an adult is 0.5 milligrams per kilogram per hour (mg/kg/h) or more. With acute kidney failure, the output will drop below 0.5 mg/kg/h.8 How is creatinine used to diagnose acute renal failure? Creatinine is a byproduct of muscle metabolism excreted in urine. If acute renal failure is suspected, a serum creatinine (SCr) blood test can measure how much and how quickly this byproduct is accumulating. Acute renal failure can be diagnosed either when the SCr increases by 150% or more within seven days or the SCr increases by at least 0.3 milligrams per deciliter (mg/dL) within 48 hours.8 How is the glomerular filtration rate (GFR) used for acute renal failure? Glomeruli are tiny structures in the kidneys that filter blood. The glomerular filtration rate (GFR) is a blood test used to calculate how effectively your glomeruli are working based on your age, height, weight, sex, and race. The GFR plays an important role in the staging of acute renal failure.9 What other blood tests are used for acute renal failure? In addition to serum creatinine, blood tests can detect if there are abnormal levels of other substances in the bloodstream. This includes a blood urea nitrogen (BUN) test that measures a waste product called urea nitrogen, and a serum potassium test that can detect excessive and potentially dangerous accumulations of potassium. How is ultrasound used in the diagnosis of acute renal failure? Ultrasound can help diagnose the cause of acute renal failure. It is the preferred method of imaging that can detect things like kidney damage, blood clots, ruptured vessels, blood or urine obstruction, tumors, and other causes of kidney failure. What does staging mean in relation to acute renal failure? Staging is used to determine the severity of acute renal failure. The staging can be based on the RIFLE criteria, which categorizes the severity by class R (risk of failure), class I (kidney injury), or class F (kidney failure). A similar system called AKIN categorizes it by stages 1, 2, and 3. The determination is based on the results of SCr, urine volume, or GFR tests. What are the symptoms? Symptoms of acute renal failure may include: Little or no urine when you urinate. Swelling, especially in your legs and feet. Not feeling like eating. Nausea and vomiting. Feeling confused, anxious and restless, or sleepy. Pain in the back just below the rib cage. This is called flank pain. Some people may not have any symptoms. What are the risk factors? What increases your risk for acute renal failure? Being diagnosed: How will your doctor diagnose acute renal failure? What is the difference between acute renal failure and chronic kidney disease? How is acute renal failure diagnosed? Your doctor will ask about symptoms you may have, what medicines you take, and what tests you have had. Your symptoms can help point to the cause of your kidney problem. Blood and urine tests can check how well your kidneys are working. A chemistry screen can show if you have normal levels of sodium (salt), potassium, and calcium. You may also have an ultrasound. This imaging test lets your doctor see your kidneys. If you are already in the hospital, tests done for other problems also may find kidney failure. Getting treatment: How is acute renal failure treated? Ongoing concerns: What is uremic syndrome? What is dialysis? Living with acute renal failure: Do I need to change the way I eat? Does acute renal failure cause lasting problems? How is it treated? Your doctor or a kidney specialist (nephrologist) will try to treat the problem that is causing your kidneys to fail. At the same time, the doctor will try to: Stop wastes from building up in your body. You may have dialysis. This treatment uses a machine to do the work of your kidneys until they recover. It will help you feel better. Prevent other problems. You may take antibiotics to prevent or treat infections. You also may take other medicines to get rid of extra fluid and keep your body’s minerals in balance. You can help yourself heal by taking your medicines as your doctor tells you to. You also may need to follow a special diet to keep your kidneys from working too hard. You may need to limit sodium, potassium, and phosphorus. A dietitian can help you plan meals. Does acute renal failure cause lasting problems? About half the time, doctors can fix the problems that cause kidney failure in a few days or weeks. These people’s kidneys will work well enough for them to live normal lives. But other people may have permanent kidney damage that leads to chronic kidney disease. Older people and those who are very sick from other health problems may not get better. People who die usually do so because of the health problem that caused their kidneys to fail. What is a dialysis machine? A dialysis machine is a machine that cleans the blood of toxins when the kidneys are not working. The patient's blood enters the dialysis machine and goes through a special filter that works like the kidney to remove fluid and toxins from the blood. The use of the dialysis machine is termed hemodialysis. A patient undergoing hemodialysis must be connected to the hemodialysis machine by tubing that allows blood to flow to and from the dialysis machine. The tubing is connected to the patient by way of a dialysis shunt or catheter. When is a dialysis machine used? A dialysis machine is used when a patient's kidneys cannot effectively clean the blood. Does use of a dialysis machine hurt? The use of the dialysis machine does not hurt. How long is a dialysis machine used? The dialysis machine can be used for a short period of time or for a long period of time, depending on what is wrong with the kidneys. Are there any potential complications associated with use of a dialysis machine? The potential complications associated with the use of the dialysis machine are very uncommon and include bleeding and infection. During dialysis a patient's blood pressure may vary due to the fluid shifts. |