Definition of Renal Failure
Renal failure (also kidney failure or renal insufficiency) is a medical condition in which the kidneys fail to adequately filter waste products from the blood. 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.
Renal failure is mainly determined by a decrease in glomerular filtration rate, the rate at which blood is filtered in the glomeruli of the kidney. This 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 renal 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.
Renal failure can be divided into two categories: acute kidney injury or chronic kidney disease. The type of renal failure is determined by the trend in the serum creatinine. Other factors that may help differentiate acute kidney injury from chronic kidney disease include anemia and the kidney size on ultrasound. Chronic kidney disease generally leads to anemia and small kidney size.
Acute Kidney İnjury
Acute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine 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. The underlying cause must be identified and treated to arrest the progress, and dialysismay 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. CKD can be the long term consequence of irreversible acute disease or part of a disease progression.
Acute-on-chronic Renal Failure
Acute kidney injuries can be present on top of chronic kidney disease, a condition called acute-on-chronic renal 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 renal 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.
Cause of Renal Failure
Acute Renal Failure
Acute kidney failure usually occurs when the blood supply to the kidneys is suddenly interrupted or when the kidneys become overloaded with toxins. Causes of acute failure 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 failure. Unlike chronic kidney disease, however, the kidneys can often recover from acute failure, allowing the patient to resume a normal life. People suffering from acute failure 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 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. 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 aspirin, ibuprofen, and acetaminophen (paracetamol) can also cause chronic kidney damage.
Some infectious diseases, such as hantavirus, can attack the kidneys, causing kidney failure.
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.
Signs and Symptoms of Renal Failure
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). Renal failure accompanied by noticeable symptoms is termed uraemia.
Symptoms of kidney failure include:
- High levels of urea in the blood, which can result in:
- Vomiting and/or diarrhea, which may lead to dehydration
- 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 build up of phosphates in the blood that diseased kidneys cannot filter out may cause:
- Bone damage
- Nonunion in broken bones
- Muscle cramps (caused by low levels of calcium which can be associated with hyperphosphatemia)
- A build up of potassium in the blood that diseased kidneys cannot filter out (called hyperkalemia) may cause:
- Abnormal heart rhythms
- Muscle paralysis
- 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:
- 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, a condition known as anemia. This can result in:
- Feeling tired and/or weak
- Memory problems
- Difficulty concentrating
- 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, or face
- Other symptoms include:
- Appetite loss, a bad taste in the mouth
- Difficulty sleeping
- Darkening of the skin
- Excess protein in the blood
- With high dose penicillin, renal failure patients may experience seizures
Risk Factors for Renal Failure
Acute kidney failure almost always occurs in connection with another medical condition or event. These conditions can increase your risk of acute kidney failure:
- Being hospitalized, especially for a serious condition that requires intensive care
- Advanced age
- Blockages in the blood vessels in your arms or legs (peripheral artery disease)
- Heart or belly surgery or a bone marrow transplant
- High blood pressure
- Heart failure
- Kidney diseases
- Liver diseases
Diagnosis of Renal Failure
Measurement for CKD
Stages of Kidney Failure
Chronic kidney failure is measured in five stages, which are calculated using a patient’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. Patients in stages 4 and 5 usually require preparation of the patient 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 whenever feasible.
Glomerular Filtration Rate
A normal GFR varies according to many factors, including sex, age, body size and race. Renal professionals consider the glomerular filtration rate (GFR) to be the best overall index of kidney function. The National Kidney Foundation 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).
Prevention from Renal Failure
Acute kidney failure is often difficult to predict or prevent. But you may reduce your risk by taking care of your kidneys. Try to:
- Follow instructions on over-the-counter (OTC) medications. Follow the instructions on OTC pain medications such as aspirin, acetaminophen (Tylenol, others) and ibuprofen (Advil, Motrin IB, others). Taking too high doses may increase your risk of acute kidney failure. This is especially true if you have pre-existing kidney disease, diabetes or high blood pressure.
- Treat disorders that causes kidney problems. Some diseases or conditions increase the risk of acute kidney failure, such as diabetes or high blood pressure, follow your doctor’s recommendations for managing your condition.
- Maintain a healthy lifestyle. Control the weight. Be active; eat a sensible, balanced diet; and avoid drinking alcohol to excess habitually.
Treatment of Renal Failure
Depending on the underlying cause, some types of chronic kidney failure can be treated. Treatment consists of measures to help control signs and symptoms of chronic kidney failure, reduce complications, and slow the progress of the disease. If your kidneys become severely damaged, you may need treatments for end-stage kidney disease.
Kidney failure complications can be controlled to make you more comfortable. Treatments may include:
- High blood pressure medications
- Medications to lower cholesterol levels
- Medicines given through a vein to help control your blood potassium level
- Medications to relieve anemia
- Medications to relieve swelling
- Medications to protect your bones
- Antibiotics to treat or prevent infection
- Diuretics (“water pills”) to help remove fluid from your body.
- A lower protein diet to minimize waste products in your blood
Treatment For End-stage Kidney Disease
If your kidneys can’t keep up with waste and fluid clearance on their own and you develop complete or near-complete kidney failure, you have end-stage kidney disease. At that point, dialysis or a kidney transplant is needed.
- Dialysis: Dialysis may be needed for some patients, and can make you feel better. It helps remove toxins, excess fluids, and also excess potassium from your body while your kidneys heal. Dialysis will also be used if:
- Your mental status changes, if you stop urinating
- You develop pericarditis
- You retain too much fluid
- You cannot eliminate nitrogen waste products from your body
Dialysis will most often be short term. Rarely, the kidney damage is so great that dialysis may be permanently needed.
- Kidney transplant: If you have no life-threatening medical conditions other than kidney failure, a kidney transplant may be an option for you. Kidney transplant involves surgically placing a healthy kidney from a donor into your body. Transplanted kidneys can come from deceased donors or from living donors.
If you don’t want to have dialysis or a kidney transplant, a third option is to treat your kidney failure with conservative measures. However, your life expectancy generally would be only a few weeks in the case of complete kidney failure.