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Kidney Failure, Chronic

Definition :
Your kidneys are two bean-shaped organs, each about the size of your fist. They're located at the back of your upper abdomen, on either side of your spine. Their main function is to eliminate excess fluid and wastes from your body by filtering them out of your blood. When your kidneys lose their filtering ability, dangerous levels of fluid and waste accumulate in your body — a condition known as kidney failure.

One form of kidney failure — chronic kidney failure — usually develops slowly, with few signs or symptoms in the early stages. Many people with chronic kidney failure don't realize they have a problem until their kidney function has decreased to less than 25 percent of normal. High blood pressure and diabetes are the most common causes of chronic kidney failure.

Sometimes kidney failure happens suddenly (acute kidney failure). This is most likely to occur after complicated surgery or a severe injury, with certain medication exposure, or when blood vessels leading to your kidneys become blocked.

The main goal of treatment of chronic kidney failure is to halt or delay progression of the disease. Chronic kidney failure can progress to end-stage kidney disease, where the kidneys function at a fraction of normal capacity. At this point, you'll need either artificial filtering (dialysis) or a kidney transplant to stay alive.

Causes:
Your kidneys are part of a system that removes excess fluid and waste material from your blood. Initially, blood enters your kidneys through the kidney arteries, which are branches of your aorta — the main artery carrying oxygenated blood from your heart to the rest of your body. From there, blood moves through tiny structures in your kidneys known as nephrons.

A single kidney contains approximately 1 million nephrons, each consisting of a tuft of capillary blood vessels (glomerulus) and tiny

tubules that lead into larger collecting tubes. Each tuft of capillaries filters fluid from your bloodstream. The filtered material — which contains both waste products and substances vital for your health — passes into the tubules. From there, waste byproducts such as urea, uric acid and creatinine are excreted in your urine while substances your body needs — such as sugar, amino acids, calcium and salts — are reabsorbed back into your bloodstream.

Although this filtration system is usually able to clear all the waste products your body produces, problems can occur if blood flow to your kidneys is disrupted, if the tubules or glomeruli become damaged or diseased, or if urine outflow is obstructed.

Progressive kidney damage most often results from a chronic illness over a period of years. Common causes include :

  • Diabetes. Diabetes mellitus is a leading cause of chronic kidney failure in the United States. Chronic kidney failure is related to both type 1 and type 2 diabetes.
  • High blood pressure (hypertension). Untreated or inadequately treated high blood pressure is another common cause of chronic kidney failure in the United States. The added force of elevated blood pressure exerted on the glomeruli can cause damage and scarring. When this happens, the nephrons containing the damaged glomeruli eventually lose their ability to filter waste from your blood.
  • Obstructive nephropathy. This occurs when urine outflow is blocked over time by an enlarged prostate, kidney stones or tumors, or by vesicoureteral reflux, a condition that results from urine backing up into your kidneys from your bladder. The backflow pressure in your kidneys reduces their function.
  • Kidney diseases. These include clusters of cysts in the kidneys (polycystic kidney disease), kidney infection (pyelonephritis) and inflammation of the glomeruli (glomerulonephritis), a condition that causes your kidneys to leak protein into your urine and damages nephrons.
  • Kidney (renal) artery stenosis. This is a narrowing or blockage of the kidney artery before it enters your kidney. In older adults, blockages often result when fatty deposits accumulate under the lining of the artery walls (atherosclerosis). Kidney artery stenosis can also affect young women in the form of a condition known as fibromuscular dysplasia, which causes the walls of the arteries to become thicker. Both conditions are often associated with high blood pressure.
  • Toxins. Ongoing exposure to fuels and solvents, such as carbon tetrachloride, and lead — in lead-based paint, lead pipes, soldering materials, jewelry and even alcohol distilled in old car radiators — can lead to chronic kidney failure.

Risk factors :
Diabetes is the single greatest risk factor for chronic kidney failure in the United States. Other conditions that increase your risk of kidney failure include :

  • High blood pressure (hypertension)
  • Sickle cell disease
  • Lupus erythematosus
  • Atherosclerosis
  • Chronic glomerulonephritis
  • Congenital kidney disease
  • Kidney disease present at birth (congenital)
  • Bladder outlet obstruction
  • Overexposure to toxins and to some medications

When to seek medical advice :
If you have a chronic medical condition that puts you at increased risk of chronic kidney failure, your doctor is likely to monitor your blood pressure and kidney function with urine and blood tests during regularly scheduled office visits.

Call your doctor if you experience any of the signs and symptoms of chronic kidney failure between visits. These may include a change in urination patterns or quantity, dark or cola-colored urine, unexplained weight loss, nausea or vomiting, fatigue, headaches or a yellowish-brown cast to your skin. Even if you have no risk factors for kidney failure, see your doctor immediately if you notice that you're urinating much more or much less than usual or if you see any blood in your urine.

Symptoms :
Chronic kidney failure can be difficult for you or your doctor to detect initially. Signs and symptoms are often nonspecific, meaning they can also be attributed to other illnesses. In addition, because your kidneys are highly adaptable and able to compensate for lost function, signs and symptoms of chronic kidney failure may not appear until irreversible damage has occurred. Signs and symptoms include :

  • High blood pressure
  • Unexplained weight loss
  • Anemia
  • Nausea or vomiting
  • A general sense of discomfort and unease (malaise)
  • Fatigue
  • Headaches that seem unrelated to any other cause
  • Decreased mental sharpness
  • Muscle twitches and cramps
  • Bloody or tarry stools, which could indicate bleeding in your intestinal tract
  • Yellowish-brown cast to your skin
  • Persistent itching

Diagnosis:
If you have diabetes, your doctor will likely schedule an annual test to measure small amounts of protein in your urine (microalbuminuria). This test can screen for early kidney damage related to diabetes (diabetic nephropathy).

If your doctor suspects chronic kidney failure, he or she is likely to order urine and blood tests to check for increased levels of waste products, such as urea and creatinine. You also may have a chest X-ray to check for fluid retained in your lungs (pulmonary edema) as well as tests to rule out other possible causes for your signs and symptoms.

To help confirm a diagnosis of kidney failure, you may have the following tests :

  • Ultrasound imaging. This test uses high-frequency sound waves and computer technology to generate images of your kidneys. Ultrasound images can indicate the shape and structure of your kidneys and reveal obstructions contributing to the problem.
  • Computerized tomography (CT) scan. This test uses computers to create more detailed images of your internal organs — including your kidneys — than conventional X-rays do.
  • Magnetic resonance imaging (MRI). Instead of X-rays, this test uses magnetic fields and radio waves to generate cross-sectional pictures of your body.
  • Kidney biopsy. Sometimes your doctor may remove a small sample of kidney tissue to be examined microscopically. Kidney tissue analysis permits a more specific diagnosis of the kidney disease.

Your doctor confirms a diagnosis of end-stage kidney disease when blood tests consistently show very high levels of urea and creatinine — a sign that kidney function has been severely and permanently damaged.

Complications :
Chronic kidney failure can affect almost every part of your body. Potential complications may include :

  • Fluid retention. This may lead to swollen tissues, congestive heart failure or fluid in your lungs (pulmonary edema).
  • A sudden rise in potassium levels in your blood (hyperkalemia). This could impair your heart's ability to function and may be life-threatening.
  • Weak bones that fracture easily.
  • Anemia.
  • Stomach ulcers.
  • Dry skin, changes in skin color.
  • Insomnia.
  • Damage to your central nervous system.
  • Decreased immune response, leaving you more vulnerable to infection.
  • Pericarditis, an inflammation of the sac-like membrane that envelops your heart (pericardium).
  • End-stage kidney disease, characterized by irreversible damage to your kidneys. This requires either dialysis or a kidney transplant for survival.

Complications in children
One of the most serious complications affecting children with chronic kidney failure is a failure to grow. In addition to regulating fluids and ridding the body of waste, the kidneys produce a hormone (erythropoietin) that helps generate red blood cells and metabolize human growth hormone. The kidneys also regulate the interactions of calcium and vitamin D, both of which are essential for bone growth.

Complications during pregnancy
If you're a woman with chronic kidney failure who becomes pregnant, you'll face a number of potential complications. That's because your kidneys must work especially hard to deal with the extra fluids of pregnancy. This may lead to worsening high blood pressure and an increase in the waste products circulating in your blood.

These changes affect both you and your baby. Chronic high blood pressure means your baby receives less blood through the placenta, which can seriously affect growth. And waste products in your bloodstream may harm your baby's health.

In addition, pregnant women with chronic kidney failure are at high risk of preeclampsia, a serious condition of late pregnancy. Preeclampsia causes a dangerous rise in blood pressure. If not treated, it can lead to hemorrhages in the brain, liver or kidneys and ultimately may be fatal for both you and your baby.

Treatment:
Chronic kidney failure has no cure, but treatment can help control signs and symptoms, reduce complications, and slow the progress of the disease. If you have chronic kidney failure, your primary doctor will likely refer you to a kidney specialist (nephrologist), if you aren't seeing one already.

Treating the underlying condition

The first priority is controlling the condition responsible for your kidney failure and its complications. If you have diabetes or high blood pressure (hypertension), for instance, that means carefully following your doctor's recommendations for diet and exercise and taking any medications as directed. Most people with chronic kidney failure are treated with medications to lower their blood pressure — commonly angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers — and to preserve kidney function. To protect kidney function, your blood pressure may need to be lower than if your kidneys were functioning normally.

In addition, following a proper diet is extremely important in treating kidney failure itself. Restricting the amount of protein you eat may help slow the progress of the disease. It can also help ease such symptoms as nausea, vomiting and lack of appetite. You'll likely need to limit the amount of salt in your diet to help control high blood pressure. Over time, you may also need to restrict the amount of potassium and phosphorus you consume.

Your doctor may also recommend that you avoid substances that can be toxic to your kidneys, such as nonsteroidal anti-inflammatory drugs and contrast dyes used with certain X-rays.

Treating complications
You'll also need treatment for complications of chronic kidney failure. For example, anemia may require supplements of the hormone erythropoietin to induce production of more red blood cells. In addition, your doctor may prescribe a form of vitamin D (calcitriol) to prevent weak bones, as well as a phosphate-binding medication to lower the amount of phosphate in your blood. Phosphate binds to calcium in your body thus reducing the amount of calcium available for your bones, making them weak and vulnerable to fracture.

End-stage kidney disease
By the time end-stage kidney disease develops, your kidneys are functioning at less than 10 percent to 15 percent of capacity. At this point, the conservative measures used to treat chronic kidney failure — diet, medications and controlling the underlying cause and complications — are no longer enough. Your kidneys aren't able to keep up with waste and fluid clearance on their own, and dialysis or a kidney transplant becomes the only option to support life.

The exact point at which this is needed varies from person to person. In most cases, doctors try to manage chronic kidney failure as long as possible because both dialysis and transplantation are serious undertakings that can be life-threatening. Eventually, however, a time may come when their benefits outweigh their risks.

Dialysis is an artificial means of removing waste products and extra fluid from your blood when your kidneys aren't able to do this on their own. It's not a miracle treatment, and it presents significant risks, including infection. Still, it can help prolong life for people with end-stage kidney disease.

There are several different types of kidney dialysis. They include :

  • Hemodialysis. The most common form of dialysis is known as hemodialysis. It removes extra fluids, chemicals and wastes from your bloodstream by filtering your blood through an artificial kidney (dialyzer). Blood is pumped out of your body to the artificial kidney through a vascular access that's created surgically, usually in your arm or leg. Your blood plasma moves across membranes inside the artificial kidney that filter out waste. Less than 1 cup of blood is outside your body at any one time. Most people require approximately 12 hours of dialysis each week, usually divided into three sessions.
  • Peritoneal dialysis. Instead of filtering your blood through a machine, this type of dialysis uses the vast network of tiny blood vessels in your own abdomen (peritoneal cavity) to filter your blood. First, a small, flexible tube (catheter) is implanted into your abdomen. Then, a dialysis solution is infused into and drained out of your abdomen for as long as is necessary to remove waste and excess fluid.
  • Continuous ambulatory peritoneal dialysis. You perform this type of dialysis yourself at home, exchanging the dialysis solution in your abdomen four times a day, seven days a week. You space out these exchanges throughout the day.
  • Continuous cycling peritoneal dialysis. In this type of dialysis, a machine (cycler machine) automatically infuses dialysis solution into and out of your peritoneal cavity over a period of 10 to 12 hours while you sleep.

Kidney transplant
If you have no other life-threatening medical conditions, a kidney transplant is usually a better option than dialysis because it provides a better quality of life. But you may need dialysis until a suitable kidney donor is found. Finding the right donor may be difficult, however.

The more closely the donor matches your blood type, cell-surface proteins and antibodies, the less likely your body is to reject the new kidney. A sibling is likely to be the best donor. If this isn't possible, another blood relative, such as a parent, aunt, uncle or cousin, or even a non-blood-related adult may be considered. When a living donor isn't available, tissue-typing centers throughout the country may search for a cadaver kidney from an accident victim or other person who has offered to donate organs after his or her death.

Prevention:
It's often not possible to prevent kidney failure. But you may reduce your risk by following these suggestions :

  • Don't abuse alcohol or other drugs, including over-the-counter pain medications such as aspirin, acetaminophen and ibuprofen. Avoid long-term exposure to heavy metals, such as lead, as well as to solvents, fuels and other toxic substances.
  • Carefully follow all of your doctor's recommendations for managing your condition if you have a chronic medical condition that increases your risk of kidney failure. The American Diabetes Association recommends yearly prealbumin urine tests for most people with diabetes.
  • Consider a pre-pregnancy consultation if you have chronic kidney failure and are thinking of becoming pregnant. Talk with a knowledgeable obstetrician or nephrologist to discuss your risks. If you're already pregnant, be sure to get comprehensive medical care — including prenatal visits every two weeks for at least the first 32 weeks.
 
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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