Kidney failure

Kidney failure is described in two ways: acute or chronic. Acute kidney failure occurs when illness, infection, or injury damages the kidneys. Temporarily, the kidneys cannot adequately remove fluids and wastes from the body or maintain the proper level of certain kidney-regulated chemicals in the bloodstream. Similarly, chronic kidney failure occurs when a number of diseases or inherited disorders injure the kidneys, but this form leads to irreversible damage, and eventually total kidney failure or end-stage renal disease (ESRD). Without proper treatment intervention to remove wastes and fluids from the bloodstream, ESRD is fatal.

The kidneys are the body's natural filtration system. They perform the critical task of processing approximately 200 quarts of fluid in the bloodstream every 24 hours. Waste products like urea and toxins, along with excess fluids,are removed from the bloodstream in the form of urine. Kidney (or renal) failure occurs when kidney functioning becomes impaired. Fluids and toxins beginto accumulate in the bloodstream. As fluids build up in the bloodstream, thepatient with acute kidney failure may become puffy and swollen (edematous) inthe face, hands, and feet. Their blood pressure typically begins to rise, and they may experience fatigue and nausea.

Unlike chronic kidney failure, which is long term and irreversible, acute kidney failure is a temporary condition. With proper and timely treatment, it can typically be reversed. Often there is no permanent damage to the kidneys. Acute kidney failure appears most frequently as a complication of serious illness, like heart failure, liver failure, dehydration, severe burns, and excessive bleeding (hemorrhage). It may also be caused by an obstruction to the urinary tract or as a direct result of kidney disease, injury, or an adverse reaction to a medicine.

Acute kidney failure can be caused by many different illnesses, injuries, andinfections. These conditions fall into three main categories: prerenal, postrenal, and intrarenal conditions.

Prerenal conditions do not damage the kidney, but can cause diminished kidneyfunction. They are the most common cause of acute renal failure, and include: dehydration; hemorrhage, or excessive bleeding; septicemia, or sepsis (a poisoning of the blood); heart failure; liver failure; and burns.

Postrenal conditions cause kidney failure by obstructing the urinary tract. These conditions include: inflammation of the prostate gland in men (prostatitis); enlargement of the prostate gland (benign prostatic hypertrophy); bladder or pelvic tumors; and kidney stones(calculi).

Intrarenal conditions involve kidney disease or direct injury to the kidneys.These conditions include: lack of blood supply to the kidneys (ischemia); the use of radiocontrast agents during diagnostic tests in patients with kidneyproblems; drug abuse or overdose; long-term use of nephrotoxic medications,like certain pain medicines; acute inflammation of the glomeruli, or filters,of the kidney; and kidney infections

Kidney failure is triggered by disease or a hereditary disorder in the kidneys. Both kidneys are typically affected. The four most common causes of chronic kidney failure include: diabetes, which consists of diabetes mellitus (DM),both insulin dependant (IDDM) and non-insulin dependant (NIDDM), a conditionthat occurs when the body cannot produce and/or use insulin, the hormone necessary for the body to process glucose; glomerulonephritis, or the chronic inflammation of the glomeruli, or filtering units of the kidney. Certain typesof glomerulonephritis are treatable, and may only cause a temporary disruption of kidney functioning; hypertension, or high blood pressure is unique to chronic kidney failure in that it is both a cause and a major symptom of the condition.

Other possible causes of chronic kidney failure include kidney cancer, obstructions such as kidney stones, pyelonephritis (inflammation within kidney and of the surrounding pelvis), reflux nephropathy, systemic lupus erythematosus, amyloidosis, sickle-cell anemia, Alport syndrome, and oxalosis.

Initially, symtpoms of chronic kidney failure develop slowly. Even individuals with mild to moderate kidney failure may show few symtpoms in spite of increased urea in their blood. Among the symptoms that may be present at this point are frequent urination during the night and high blood pressure.

Initially, symtpoms of chronic kidney failure develop slowly. Even individuals with mild to moderate kidney failure may show few symtpoms in spite of increased urea in their blood. Among the symptoms that may be present at this point are frequent urination during the night and high blood pressure.

There are several symptoms of acute and chronic kidney failure, but most symptoms of chronic kidney failure are not apparent until kidney disease has progressed significantly. Common symptoms for both acute and chronic conditions include:

  • Anemia. The kidneys are responsible for the productionof erythropoietin (EPO), a hormone which stimulates red cell production. If kidney disease causes shrinking of the kidney, this red cell production is hampered.
  • Bad breath or a bad taste in mouth. Urea, or waste products,in the saliva may cause an ammonia-like taste in the mouth.
  • Bone andjoint problems. The kidneys produce vitamin D, which aids in the absorptionof calcium and keeps bones strong. For patients with kidney failure, bones may become brittle, and in the case of children, normal growth may be stunted.Joint pain may also occur as a result of unchecked phosphate levels in the blood.
  • Edema. Puffiness or swelling around the eyes, arms, hands, andfeet.
  • Frequent urination.
  • Foamy or bloody urine. Protein inthe urine may cause it to foam significantly. Blood in the urine may indicate bleeding from diseased or obstructed kidneys, bladder, or ureters.
  • Headaches. High blood pressure may trigger headaches.
  • Hypertension,or high blood pressure. The retention of fluids and wastes causes blood volume to increase, which in turn, causes blood pressure to rise.
  • Increased fatigue. Toxic substances in the blood and the presence of anemia may cause feelings of exhaustion.
  • Itching. Phosphorus, which is typically eliminated in the urine, accumulates in the blood of patients with kidney failure. This heightened phosphorus level may cause itching of the skin.
  • Lower back pain. Pain where the kidneys are located, in the small of the back below the ribs.
  • Nausea, loss of appetite, and vomiting. Urea in the gastric juices may cause upset stomach. This can lead to malnutrition and weight loss.

Kidney failure is typically diagnosed and treated by a nephrologist, a doctorthat specializes in treating the kidneys. The patient that is suspected of having kidney failure will undergo an extensive blood work-up. A blood test will assess the levels of creatinine, blood urea nitrogen (BUN), uric acid, phosphate, sodium, and potassium in the blood. Urine samples will also be collected, usually over a 24-hour period, to assess protein loss and/or creatinineclearance.

Determining the cause of kidney failure is critical to proper treatment. A full assessment of the kidneys is necessary to determine if the underlying disease is treatable and if the kidney failure is chronic or acute. X rays, magnetic resonance imaging (MRI), computed tomography scan (CT), ultrasound, renal biopsy, and/or arteriogram of the kidneys may be used to determine the cause of kidney failure and level of remaining kidney function. X rays and ultrasound of the bladder and/or ureters may also be needed.

Treatment for acute kidney failure varies. Treatment is directed to the underlying, primary medical condition that has triggered kidney failure. Prerenalconditions may be treated with replacement fluids given through a vein, diuretics, blood transfusion, or medications. Postrenal conditions and intrarenalconditions may require surgery and/or medication.

Frequently, patients in acute or chronic kidney failure require hemodialysis, hemofiltration, or peritoneal dialysis to filter fluids and wastes from the bloodstream until the primary medical condition can becontrolled.

A primary type of treatment for both acute and chronic kidney failure is hemodialysis which involves circulating the patient's blood outside of the body through an extracorporeal circuit (ECC), or dialysis circuit. The ECC is madeup of plastic blood tubing, a filter known as a dialyzer (or artificial kidney), and a dialysis machine that monitors and maintains blood flow and administers dialysate. Dialysate is a sterile chemical solution that is used to drawwaste products out of the blood. The patient's blood leaves the body throughthe vein and travels through the ECC and the dialyzer, where fluid removal takes place.

During dialysis, waste products in the bloodstream are carried out of the body. At the same time, electrolytes and other chemicals are added to the blood.The purified, chemically-balanced blood is then returned to the body.

A dialysis "run" typically lasts three to four hours, depending on the type of dialyzer used and the physical condition of the patient. Dialysis is used several times a week until acute kidney failure is reversed.

Blood pressure changes associated with hemodialysis may pose a risk for patients with heart problems. Peritoneal dialysis may be the preferred treatment option in these cases.

Another type of treatment is hemofiltration, also known as continuous renal replacement therapy (CRRT). This procedure is a slow, continuous blood filtration therapy used to control acute kidney failure in critically ill patients.These patients are typically very sick and may have heart problems or circulatory problems. They cannot handle the rapid filtration rates of hemodialysis.They also frequently need antibiotics, nutrition, vasopressors, and other fluids given through a vein to treat their primary condition. Because hemofiltration is continuous, prescription fluids can be given to patients in kidney failure without the risk of fluid overload.

Like hemodialysis, hemofiltration uses an ECC. A hollow fiber hemofilter is used instead of a dialyzer to remove fluids and toxins. Instead of a dialysismachine, a blood pump makes the blood flow through the ECC. The volume of blood circulating through the ECC in hemofiltration is less than that in hemodialysis. Filtration rates are slower and gentler on the circulatory system. Hemofiltration treatment will generally be used until kidney failure is reversed.

If an acute kidney failure patient is stable and not in immediate crisis, peritoneal dialysis may be used. In peritoneal dialysis (PD), which is also usedas a treatment for chronic kidney failure, the lining of the patient's abdomen, the peritoneum, acts as a blood filter. A flexible tube-like instrument (catheter) is surgically inserted into the patient's abdomen. During treatment, the catheter is used to fill the abdominal cavity with dialysate. Waste products and excess fluids move from the patient's bloodstream into the dialysate solution. After a certain time period, the waste-filled dialysate is drained from the abdomen, and replaced with clean dialysate. There are three type of peritoneal dialysis, which vary according to treatment time and administration method.

Peritoneal dialysis is often the best treatment option for infants and children. Their small size can make vein access difficult to maintain. It is not recommended for patients with abdominal adhesions or other abdominal defects (like a hernia) that might reduce the efficiency of the treatment. It is also not recommended for patients who suffer frequent bouts of an inflammation of the small pouches in the intestinal tract (diverticulitis).

Kidney transplantation involves surgically attaching a functioning kidney, orgraft, from a brain dead organ donor (a cadaver transplant), or from a living donor, to a patient with ESRD. Patients with chronic renal disease who needa transplant and don't have a living donor register with UNOS (United Network for Organ Sharing), the federal organ procurement agency, to be placed on awaiting list for a cadaver kidney transplant. Kidney availability is based on the patient's health status. When the new kidney is transplanted, the patient's existing, diseased kidneys may or may not be removed, depending on the circumstances surrounding the kidney failure. A regimen of immunosuppressive,or anti-rejection medication, is required after transplantation surgery.

A diet low in sodium, potassium, and phosphorous, three substances that the kidneys regulate, is critical in managing kidney disease Other dietary restrictions, such as a reduction in protein, may be prescribed depending on the cause of kidney failure and the type of dialysis treatment employed. Patients with chronic kidney failure also need to limit their fluid intake.

Kidney failure patients with hypertension typically take medication to control their high blood pressure. Epoetin alfa, or EPO (Epogen), a hormone therapy, and intravenous or oral iron supplements are used to manage anemia. A multivitamin may be prescribed to replace vitamins lost during dialysis treatments. Vitamin D, which promotes the absorption of calcium, along with calcium supplements, may also be prescribed.

Since 1973, Medicare has picked up 80% of ESRD treatment costs, including thecosts of dialysis and transplantation and of some medications. To qualify for benefits, a patient must be insured or eligible for benefits under Social Security, or be a spouse or child of an eligible American. Private insurance and state Medicaid programs often cover the remaining 20% of treatment costs.

Early diagnosis and treatment of kidney failure is critical to improving length and quality of life in chronic kidney failure patients. Patient outcome varies by the cause of chronic kidney failure and the method chosen to treat it. Overall, patients with chronic kidney disease leading to ESRD have a shortened life span. According to the United States Renal Data System (USRDS), thelife span of an ESRD patient is 18-47% of the life span of the age-sex-race matched general population. ESRD patients on dialysis have a life span that is16-37% of the general population

The demand for kidneys to transplant continues to exceed supply. In 1996, over 34,000 Americans were on the UNOS waiting list for a kidney transplant, butonly 11,330 living donor and cadaver transplants were actually performed. Cadaver kidney transplants have a 50% chance of functioning 9 years, and livingdonor kidneys that have two matching antigen pairs have a 50% chance of functioning for 24 years. However, some transplant grafts have functioned for over 30 years.

Because many of the illnesses and underlying conditions that often trigger acute kidney failure are critical, the prognosis for these patients many timesis not good. Studies have estimated overall death rates for acute kidney failure at 42-88%. Many people, however, die because of the primary disease thathas caused the kidney failure. These figures may also be misleading because patients who experience kidney failure as a result of less serious illnesses (like kidney stones or dehydration) have an excellent chance of complete recovery. Early recognition and prompt, appropriate treatment are key to patient recovery.

Up to 10% of patients who experience acute kidney failure will suffer irreversible kidney damage. They will eventually go on to develop chronic kidney failure or end-stage renal disease. These patients will require long-term dialysis or kidney transplantation to replace their lost renal functioning.

Since acute kidney failure can be caused by many things, prevention is difficult. Medications that may impair kidney function should be given cautiously.Patients with pre-existing kidney conditions who are hospitalized for other illnesses or injuries should be carefully monitored for kidney failure complications. Treatments and procedures that may put them at risk for kidney failure (like diagnostic tests requiring radiocontrast agents or dyes) should be used with extreme caution.

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