Five Types of Kidney FailureThere are five different types of kidney failure:
Acute Prerenal Kidney Failure
Insufficient blood flow to the kidneys can cause acute prerenal kidney failure. The kidneys can’t filter toxins from the blood without enough blood flow. This type of kidney failure can usually be cured once the cause of the decreased blood flow is determined.
Acute Intrinsic Kidney Failure
Acute intrinsic kidney failure can be caused by direct trauma to the kidneys, such as physical impact or an accident. Causes also include toxin overload and ischemia, which is a lack of oxygen to the kidneys. Ischemia may be caused by:
- severe bleeding
- shock
- renal blood vessel obstruction
- glomerulonephritis, which is an inflammation of the tiny filters in your kidneys
Chronic Prerenal Kidney Failure
When there isn’t enough blood flowing to the kidneys for an extended period of time, the kidneys begin to shrink and lose the ability to function.
Chronic Intrinsic Kidney Failure
This happens when there is long-term damage to the kidneys due to intrinsic kidney disease. Intrinsic kidney disease is caused by a direct trauma to the kidneys, such as severe bleeding or a lack of oxygen.
Chronic Post-Renal Kidney Failure
A long-term blockage of the urinary tract prevents urination, which causes pressure and eventual kidney damage.
Part 4 of 7: Symptoms
What Are the Symptoms of Kidney Failure?Many different symptoms can be signs of kidney failure. No symptoms are present sometimes, but usually someone with kidney failure will see a few signs of the disease. Possible symptoms include:
- a reduced amount of urine
- swelling of your legs, ankles, and feet from retention of fluids caused by the failure of your kidneys to eliminate water waste
- unexplained shortness of breath
- excessive drowsiness or fatigue
- persistent nausea
- confusion
- pain or pressure in your chest
- seizures
- a coma
How Is Kidney Failure DiagnosedThere are several tests that can be used to diagnose kidney failure. These include:
Urinalysis
A urine sample can be tested for any abnormalities, including abnormal protein or sugar that spills into the urine. Your doctor may perform a urinary sediment examination, which will measure the amount of red and white blood cells, look for high levels of bacteria, and search for high numbers of cellular casts.
Urine Volume Measurements
Measuring urine output is one of the simplest tests to help diagnose kidney failure. For example, low urinary output may suggest that kidney disease is due to a urinary blockage, which can be caused by multiple illnesses or injuries.
Blood Samples
Samples of your blood are taken to measure substances that are filtered by your kidneys, such as blood urea nitrogen (BUN) and creatinine (Cr). A rapid rise in their levels may indicate acute kidney failure.
Imaging
Tests such as ultrasounds, MRI, and CT scans provide images of the kidneys themselves, along with the urinary tract. This allows your doctor to look for blockages or abnormalities in your kidneys.
Kidney Tissue Sample
Tissue samples are examined for abnormal deposits, scarring, or infectious organisms. A kidney biopsy is used to collect the tissue sample. A biopsy is a simple procedure that’s performed, usually while you’re awake. A local anesthetic is used to eliminate any discomfort. The sample is collected with a biopsy needle inserted through your skin and down into the kidney. X-ray or ultrasound equipment is used to locate the kidneys and assist the doctor in guiding the needle.When blood flows to the kidney, sensors within specialized kidney cells regulate how much water to excrete as urine, along with what concentration of electrolytes. For example, if a person is dehydrated fromexercise or from an illness, the kidneys will hold onto as much water as possible and the urine becomes very concentrated. When adequate water is present in the body, the urine is much more dilute, and the urine becomes clear. This system is controlled by renin, a hormone produced in the kidney that is part of the fluid and blood pressure regulation systems of the body.Renal failure, also known as kidney failure or renal insufficiency, is a medical condition in which the kidneys fail to adequately filter waste products from the blood.[1] The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.
Kidney failure is mainly determined by a decrease in glomerular filtration rate, which is the rate at which blood is filtered in the glomeruli of the kidney. The condition is detected by a decrease in or absence of urine production or determination of waste products (creatinine or urea) in the blood. Depending on the cause, hematuria (blood loss in the urine) and proteinuria (protein loss in the urine) may be noted.
In kidney failure, there may be problems with increased fluid in the body (leading to swelling), increased acid levels, raised levels of potassium, decreased levels of calcium, increased levels of phosphate, and in later stages anemia. Bone health may also be affected. Long-term kidney problems are associated with an increased risk of cardiovascular disease.[2]
Acute kidney injury
Acute kidney injury (AKI), previously called acute renal failure (ARF),[3][4] is a rapidly progressive loss of renal function,[5] generally characterized by oliguria (decreased urine production, quantified as less than 400 mL per day in adults,[6] 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 asprerenal, intrinsic, and postrenal. 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 disease
Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms.[7] 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 patient to baseline kidney function, typically measured by serum creatinine. Like AKI, AoCRF can be difficult to distinguish from chronic kidney disease if the patient 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 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.[8]
Symptoms of kidney failure include the following:[8][9][10][11]
- High levels of urea in the blood, which can result in:
- Vomiting and/or diarrhea, which may lead to dehydration
- Nausea
- Weight loss
- Nocturnal urination
- 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:
- A buildup of potassium in the blood that diseased kidneys cannot filter out (called hyperkalemia) may cause:
- Abnormal heart rhythms
- Muscle paralysis[12]
- Failure of kidneys to remove excess fluid may cause:
- Swelling of the legs, ankles, feet, face and/or hands
- 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:
- 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, a condition known as anemia. This can result in:
- Feeling tired and/or weak
- Memory problems
- Difficulty concentrating
- Dizziness
- 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,[13] after which symptoms include:
- Foamy or bubbly urine
- Swelling in the hands, feet, abdomen, or face
- Other symptoms include:
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, 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 patient to resume a normal life. People suffering from acute kidney injury require supportive treatment until their kidneys recover function, and they often remain at increased risk of developing future kidney failure.[15]
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 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, and phosphorus – that are the products of rhabdomyolysis (the breakdown of skeletal muscle damaged by ischemic conditions). The specific action on the kidneys is not fully understood, but may be due in part to nephrotoxic metabolites of myoglobin.
Chronic kidney disease
Chronic kidney disease (CKD) has numerous causes. The most common causes of CKD are diabetes mellitus and long-term, uncontrolled hypertension.[16] Polycystic kidney disease is another well-known cause of CKD. The majority of people afflicted with polycystic kidney disease have a family history of the disease. Other genetic illnesses affect kidney function, as well.
Overuse of common drugs such as ibuprofen, and acetaminophen (paracetamol) can also cause chronic kidney damage.[17]
Some infectious diseases, such as hantavirus, can attack the kidneys, causing kidney failure.[18]Acute kidney failure occurs when your kidneys suddenly become unable to filter waste products from your blood. When your kidneys lose their filtering ability, dangerous levels of wastes may accumulate, and your blood's chemical makeup may get out of balance.
Acute kidney failure — also called acute renal failure or acute kidney injury — develops rapidly over a few hours or a few days. Acute kidney failure is most common in people who are already hospitalized, particularly in critically ill people who need intensive care.
Acute kidney failure can be fatal and requires intensive treatment. However, acute kidney failure may be reversible. If you're otherwise in good health, you may recover normal or nearly normal kidney function.Sometimes kidneys are no longer able to filter and clean blood. This can cause unsafe levels of waste products to build up. This is known as kidney (or renal) failure. Unless it is treated, this can cause death.
How the kidneys filter waste from your blood
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health
What are Kidneys?
The kidneys are 2 bean-shaped organs, each about the size of a fist. They are found in your back on either side of the spine. Healthy kidneys clean waste products from the blood by making urine. They also balance the amount of certain elements in your blood (such as sodium, potassium, and calcium), and make hormones that control blood pressure and red blood cells.
What is Kidney Failure?
Kidney (renal) failure is when kidneys don't work as well as they should. The term "kidney failure" covers a lot of problems. These problems can result in kidney failure:
- Your kidney doesn't get enough blood to filter
- Your kidney is hurt by a disease like
- high blood sugar (diabetes)
- high blood pressure
- glomerulonephritis (damage to the kidney's tiny filters)
- polycystic kidney disease
- Your kidney is blocked by a kidney stone or scar tissue
Kidneys are also the source of erythropoietin in the body, a hormone that stimulates the bone marrow to make red blood cells. Special cells in the kidney monitor the oxygen concentration in blood. If oxygen levels fall, erythropoietin levels rise and the body starts to manufacture more red blood cells.
- Kidneys are the organs that help filter waste products from the blood. They are also involved in regulating blood pressure, electrolyte balance, and red blood cell production in the body.
- Symptoms of kidney failure are due to the build-up of waste products in the body that may cause weakness,shortness of breath, lethargy, and confusion. Inability to remove potassium from the bloodstream may lead to abnormal heart rhythms and sudden death. Initially kidney failure may cause no symptoms.
- There are numerous causes of kidney failure, and treatment of the underlying disease may be the first step in correcting the kidney abnormality.
- Some causes of kidney failure are treatable and the kidney function may return to normal. Unfortunately, kidney failure may be progressive in other situations and may be irreversible.
- The diagnosis of kidney failure usually is made by blood tests measuring BUN, creatinine, and glomerular filtration rate (GFR).
- Treatment of the underlying cause of kidney failure may return kidney function to normal. Lifelong efforts to control blood pressure and diabetesmay be the best way to prevent chronic kidney disease and its progression to kidney failure. As we age kidney function gradually decreases over time.
