Chronic kidney failure is a gradual loss of your kidneys' filtering ability, usually due to high blood pressure or diabetes. When kidney function is seriously impaired, dangerous levels of fluid and waste can quickly accumulate in your body.

In the early stages of chronic kidney failure, you may have few signs or symptoms. 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.

The main goal of treatment of chronic kidney failure is to halt or delay progression of the disease, usually by controlling the underlying cause. Chronic kidney failure can progress to end-stage kidney disease, which is fatal without artificial filtering (dialysis) or a kidney transplant.

Signs and symptoms may include some or many of the following:

• High blood pressure
• Decreased urine output or no urine output
• Darkly colored urine
• Anemia
• Nausea or vomiting
• Loss of appetite
• Sudden weight change
• A general sense of discomfort and unease (malaise)
• Fatigue and weakness
• Headaches that seem unrelated to any other cause
• Sleep problems
• Decreased mental sharpness
• Pain along your side or mid to lower back
• Muscle twitches and cramps
• Swelling of the feet and ankles
• Bloody or tarry stools, which could indicate bleeding in your intestinal tract
• Yellowish-brown cast to your skin
• Persistent itching

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.

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Kidney cross section

Your kidneys are the key organs in the complex filtration system that removes excess fluid and waste material from the blood. Your kidneys receive blood through your renal arteries, which branch off the main artery (the abdominal aorta) carrying oxygenated blood away from your heart. On entering the kidneys, blood is distributed through smaller and smaller vessels, finally reaching tiny capillary blood vessels arranged in tufts (glomeruli).

The glomeruli filter your blood, extracting fluid, waste and substances your body needs — sugar, amino acids, calcium and salts. These filtered materials then cross into tiny tubules, from which the bloodstream reabsorbs what the body can reuse. The rest is waste, which is excreted in your urine.

Although your kidneys are 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). Elevated blood pressure can damage the glomeruli and ultimately cause the nephrons containing damaged glomeruli to lose their ability to filter waste from your blood.
• Obstruction of urine flow. An enlarged prostate, kidney stones or tumors, or vesicoureteral reflux — a condition that results when urine backs up into your kidneys from your bladder — can block urine flow, increasing pressure in your kidneys and reducing 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 artery stenosis. This is a narrowing or blockage of the kidney (renal) artery before it enters your kidney, which impairs blood flow and leads to kidney damage.
• 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.

Conditions that increase your risk of kidney failure include:

• Diabetes, which is the most common risk factor for chronic kidney failure in the United States
• High blood pressure (hypertension)
• Sickle cell disease
• Lupus erythematosus
• Atherosclerosis
• Chronic glomerulonephritis
• Kidney disease present at birth (congenital)
• Bladder outlet obstruction
• Overexposure to toxins and to some medications
• Family history of kidney disease
• Age 60 or older

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.

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 a magnetic field 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.

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

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

Complications in children
Chronic kidney failure can cause children to stop growing normally. This complication occurs partly because failing kidneys have reduced production of erythropoietin, a hormone 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. In chronic kidney failure, these interactions can become imbalanced, inhibiting growth.

Complications during pregnancy
If you have chronic kidney failure and you become pregnant, you'll face a number of potential complications. When you're pregnant, the amount of fluid in your body increases greatly, so your kidneys must work especially hard. 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. Waste products in your bloodstream may have an adverse effect on your baby as well.

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.

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Peritoneal dialysis

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. Because these medications can initially increase serum potassium and decrease overall kidney function, you may have frequent blood tests to check your potassium levels. Over the long term, these medications tend to both lower blood pressure and 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, some oral phosphate preparations used as laxatives before colonoscopy, 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. Lowering phosphate will increase the amount of calcium available for your bones so that they don't become 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, 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.

Exactly when it becomes necessary to start dialysis varies from person to person. In most cases, doctors try to manage chronic kidney failure as long as possible because both dialysis and transplantation may have potentially life-threatening complications.

Kidney dialysis
Dialysis is an artificial means of removing waste products and extra fluid from your blood when your kidneys aren't able to perform these functions. 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 two main types of kidney dialysis, each with subtypes involving slightly different techniques. They include:

• Hemodialysis. Hemodialysis 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 one of two routes — a catheter placed surgically in one of your main blood veins, or a surgically created junction between a vein and artery in your arm. Inside the artificial kidney, your blood moves across membranes that filter out waste before being returned to your body. Less than 1 cup (237 milliliters) of blood is outside your body in the dialyzer and tubing at any one time. Hemodialysis is usually performed three times a week for three or more hours.

  However, it's now recognized that more frequent dialysis — up to six times a week either during the day or at night while you sleep — results in significantly better quality of life, better control of complications and a reduction in risk of death. Newer, easy-to-use home dialysis machines are making this option more feasible for many.

• 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 peritoneal 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 peritoneal 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 life-threatening medical conditions other than kidney failure, a kidney transplant is usually a better option than dialysis, although you may need to undergo dialysis temporarily until a suitable donor kidney becomes available.

A successful kidney transplant depends on finding the best immunologic match possible. Ideally, you and the kidney's donor will have the same blood type, cell-surface proteins and antibodies. The more closely these features are matched, the lower the risk that your body will reject the new kidney. A sibling is likely to be the best donor. If that's not 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.

Chronic kidney failure is often impossible to prevent. 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 any 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.

If you have end-stage kidney disease, your doctor may ask you to limit the amount of fluids you consume every day. In most cases, limiting fluids means more than reducing your water intake. It may include cutting back on your consumption of such things as ice cubes and ice chips, coffee and tea, sodas, fruit and vegetable juices, soups, milk, cream, ice cream, sherbet, sorbet and even gelatin.

When you limit liquids, you may have a hard time controlling your thirst. The following suggestions may help you feel less thirsty:

• Suck on a lemon wedge or a few ice chips.
• Rinse your mouth with water but don't swallow it.
• Eat a piece or two of sour candy or chew gum to increase the moisture level in your mouth.