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Patient information: Chronic kidney disease (Beyond the Basics)

CHRONIC KIDNEY DISEASE OVERVIEW

Chronic kidney disease (CKD, also called kidney failure) is a condition in which the kidneys lose the ability to remove waste and excess water from the bloodstream. As waste and fluids accumulate, other body systems are affected, potentially leading to complications.

The most common causes of CKD are diabetes and high blood pressure. In the early stages of CKD, there are no obvious symptoms. The disease can progress to complete kidney failure, also called end-stage renal disease. This occurs when kidney function has worsened to the point that dialysis or kidney transplantation is required to maintain life.

The main goal of treatment is to prevent progression of CKD to complete kidney failure. The best way to do this is to diagnose and control the underlying cause.

The symptoms, evaluation, and management of CKD will be reviewed here. Kidney transplantation, peritoneal dialysis, and hemodialysis are discussed separately. (See "Patient information: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)" and "Patient information: Hemodialysis (Beyond the Basics)".)

NORMAL KIDNEY FUNCTION

A brief overview of normal kidney function can help in the understanding of chronic kidney disease (CKD). The kidneys function to remove wastes and excess water from the blood. These wastes and fluids are combined to form urine (figure 1). Many vital body functions are dependent upon the proper functioning of the kidneys.

In order for this filtering process to occur properly, the blood pressure and blood flow to the kidneys must be adequate. If the arteries leading to the kidney are diseased, the filtering process will be affected. The nephrons (figure 2), including the glomeruli and the tubules, must be healthy, and the path from the nephron to the urethra (figure 3) must not be blocked.

When the kidney filters are working properly, the result is a proper balance of fluids and chemicals in the body. If an imbalance occurs, many critical bodily functions can be affected, possibly producing symptoms associated with kidney disease. (See 'Chronic kidney disease complications' below.)

CHRONIC KIDNEY DISEASE RISK FACTORS

A number of factors can increase the risk of developing chronic kidney disease (CKD), including:

Diabetes mellitus

High blood pressure

A family history of kidney disease

African American other ethnic minorities

Obesity

Smoking

Older age

Having protein in the urine

CHRONIC KIDNEY DISEASE COMPLICATIONS

Most people with chronic kidney disease (CKD) do not have symptoms until the kidney function is severely impaired. The problem is often discovered when blood or urine tests, done for other reasons, show one or more of the abnormalities discussed above.

Even when kidney failure is advanced, most people still make a normal or near-normal amount of urine; this is sometimes confusing. Urine is being formed, but it does not contain sufficient amounts of the body's waste products.

With advanced kidney disease, you may develop edema (swelling of the feet, ankles, or legs), loss of appetite, increased sleepiness, nausea, vomiting, confusion, and difficulty thinking. Patients often develop high blood pressure; blood chemistry (electrolyte) abnormalities; anemia (a decrease in red blood cells, which can cause fatigue and other symptoms); and bone disease. (See "Patient information: Edema (swelling) (Beyond the Basics)".)

Uremia — People with advanced kidney failure may develop a group of symptoms referred to as uremia. The symptoms of uremia include loss of appetite, nausea, vomiting, swelling around the heart, nerve problems, and changes in mental status, including drowsiness, seizures, or coma.

EVALUATION AND DIAGNOSIS

A healthcare provider may use several tests to diagnose chronic kidney disease (CKD) and determine if there is a treatable underlying cause. These include the following:

Kidney function tests — The glomerular filtration rate (GFR) gives an approximate measure of the number of functioning nephrons. GFR is used to monitor the severity of kidney impairment. The most common way to estimate the GFR in adults is by measuring the creatinine level in the blood stream and then using this number to calculate an estimated GFR level. This GFR level is often shown on routine blood chemistry lab reports that your doctor obtains. A measure of kidney function can also be obtained by collecting a 24-hour urine sample and measuring the concentration of creatinine in the blood and urine.

A reduction in GFR implies either worsening of the underlying kidney disease or the development of another, occasionally reversible kidney problem.

An increase in GFR, on the other hand, indicates improvement in kidney function.

A stable GFR in people with CKD implies stable disease.

Urine tests — The presence of albumin or protein in the urine (called albuminuria or proteinuria) is a marker of kidney disease. Even small amounts of albumin in the urine may be an early sign of CKD in some people, particularly those with diabetes and high blood pressure. (See "Patient information: Protein in the urine (proteinuria) (Beyond the Basics)".)

Imaging studies — Imaging tests (such as computed tomography [CT] or ultrasound) may be recommended to determine if there are any obstructions (blockages) of the urinary tract, kidney stones, or other abnormalities. (See "Patient information: Kidney stones in adults (Beyond the Basics)".)

Kidney biopsy — In a kidney biopsy, a small piece of kidney tissue is removed and examined under a microscope. The biopsy helps to identify abnormalities in kidney tissue that may be the cause of kidney diseases. (See "Patient information: Renal (kidney) biopsy (Beyond the Basics)".)

CHRONIC KIDNEY DISEASE TREATMENT

The first step in the treatment of chronic kidney disease (CKD) is to determine the underlying cause. Some causes are reversible, including use of medications that impair kidney function, blockage in the urinary tract, or decreased blood flow to the kidneys. Treatment of reversible causes may prevent CKD from worsening.

Research has shown that management of CKD is best done with the assistance of a nephrologist, a doctor who specializes in kidney diseases. Early referral to a nephrologist decreases the chance of developing complications associated with CKD.

Hypertension — Hypertension, or high blood pressure, is present in 80 to 85 percent of people with CKD. Maintaining good blood pressure control is the most important goal for trying to slow the progression of CKD. Taking a medication called an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) reduces blood pressure and levels of protein in the urine, and is thought to slow the progression of CKD to a greater extent than some of the other medicines used to treat high blood pressure.

Sometimes, a diuretic (water pill) or other medication is also added. You may be asked to monitor your blood pressure at home to be sure that your blood pressure is well controlled. (See "Patient information: High blood pressure treatment in adults (Beyond the Basics)".)

Anemia — People with CKD are at risk for anemia. This occurs because improperly functioning kidneys produce reduced amounts of a substance called erythropoietin. Anemia can lead to fatigue and other complications.

Selected patients can be treated with drugs that stimulate production of red blood cells. You or a family member can inject these drugs at home. In some cases, iron supplements are also prescribed. (See "Anemia of chronic kidney disease: Target hemoglobin/hematocrit for patients treated with erythropoietic agents".)

Dietary changes — Changes in your diet may be recommended to control or prevent some of the complications of CKD; most important is salt restriction to help control the blood pressure.

Protein restriction — Restricting protein in the diet may slow the progression of CKD, although it is not clear if the benefits of protein restriction are worth the difficulty of sticking to a low protein diet. Although a reduced protein diet may delay dialysis for several years, the unappetizing nature of the diet is difficult for most people to tolerate. Speak to your healthcare provider about the advantages and disadvantages of a low protein diet. (See "Protein restriction and progression of chronic kidney disease".)

High potassium — Some people with CKD develop a high blood potassium level, which can interfere with normal cell function. This is frequently treated with a diuretic. Measures to prevent high potassium might also be recommended, including a low potassium diet and avoiding medicines that raise potassium levels. (See "Patient information: Low-potassium diet (Beyond the Basics)".)

High phosphate — Phosphate is a mineral that helps to keep the bones healthy. Early in the course of CKD, the body begins to retain phosphate. As the disease progresses, high blood phosphate levels can develop. This is usually treated with medicines that prevent phosphate (found in foods) from being absorbed in the digestive tract. Dietary phosphate restrictions are also recommended (table 1A-B).

High cholesterol and triglycerides — High cholesterol and triglyceride levels are common in people with kidney disease. High triglycerides have been associated with an increased risk of coronary artery disease, which can lead to heart attack.

Treatments to reduce the risk of coronary artery disease are usually recommended, including dietary changes, medications for high triglyceride and cholesterol levels, stopping smoking, and tight blood sugar control in people with diabetes. (See "Patient information: High cholesterol and lipids (hyperlipidemia) (Beyond the Basics)" and "Patient information: Quitting smoking (Beyond the Basics)" and "Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)".)

Sexual function — Men and women with advanced CKD often have difficulties with sexual function and infertility. Over 50 percent of men with end-stage kidney disease have difficulties with erection and decreased sex drive. Women often have disturbances in the menstrual cycle and fertility, usually leading to a stop in menstrual periods. Decreased sex drive may also occur in women.

You should discuss any changes in your sexual function with your healthcare provider because medications or other treatments may be effective. (See "Patient information: Sexual problems in men (Beyond the Basics)" and "Patient information: Sexual problems in women (Beyond the Basics)".)

Pregnancy — The risk that pregnancy will worsen kidney function, or that decreased kidney function will interfere with pregnancy, depends upon a number of factors. A woman with mild to moderate CKD who is considering becoming pregnant should discuss the possible risks with her nephrologist and obstetrical provider before trying to conceive.

Women with end-stage kidney disease who are on dialysis and who become pregnant are at very high risk for miscarriage, premature delivery, severe hypertension, and preeclampsia. A woman who undergoes successful renal transplantation has a lower risk of these complications. It may be advantageous for a woman to delay becoming pregnant while on hemodialysis, if renal transplantation in the near future is likely.

PREPARING FOR DIALYSIS

Some people with CKD progressively worsen over time and will eventually need dialysis. There are two types of dialysis: hemodialysis and peritoneal dialysis. Kidney transplantation is also an option for some people with CKD.

An important component of treatment for patients with CKD is planning for dialysis in advance. Although kidney transplantation is the treatment of choice in most cases, many people must wait months or years for a kidney to become available. Dialysis will likely be needed, often for an extended period.

Dialysis and kidney transplantation are discussed in detail separately. (See "Patient information: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)" and "Patient information: Hemodialysis (Beyond the Basics)" and "Patient information: Peritoneal dialysis (Beyond the Basics)".)

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Chronic kidney disease (The Basics)
Patient information: Swelling (The Basics)
Patient information: Diabetes and diet (The Basics)
Patient information: Polycystic kidney disease (The Basics)
Patient information: Hemodialysis (The Basics)
Patient information: Preparing for hemodialysis (The Basics)
Patient information: Preparing for pregnancy when you have diabetes (The Basics)
Patient information: Peritoneal dialysis (The Basics)
Patient information: Choosing between dialysis and kidney transplant (The Basics)
Patient information: Kidney transplant (The Basics)
Patient information: Planning for a kidney transplant (The Basics)
Patient information: Glomerular disease (The Basics)
Patient information: Polyarteritis nodosa (The Basics)
Patient information: Low-potassium diet (The Basics)
Patient information: Granulomatosis with polyangiitis (The Basics)
Patient information: Medicines for chronic kidney disease (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)
Patient information: Hemodialysis (Beyond the Basics)
Patient information: Glomerular disease overview (Beyond the Basics)
Patient information: Polycystic kidney disease (Beyond the Basics)
Patient information: Edema (swelling) (Beyond the Basics)
Patient information: Protein in the urine (proteinuria) (Beyond the Basics)
Patient information: Kidney stones in adults (Beyond the Basics)
Patient information: Renal (kidney) biopsy (Beyond the Basics)
Patient information: High blood pressure treatment in adults (Beyond the Basics)
Patient information: Low-potassium diet (Beyond the Basics)
Patient information: High cholesterol and lipids (hyperlipidemia) (Beyond the Basics)
Patient information: Quitting smoking (Beyond the Basics)
Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)
Patient information: Sexual problems in men (Beyond the Basics)
Patient information: Sexual problems in women (Beyond the Basics)
Patient information: Peritoneal dialysis (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Anemia of chronic kidney disease: Target hemoglobin/hematocrit for patients treated with erythropoietic agents
Antihypertensive therapy and progression of nondiabetic chronic kidney disease in adults
Assessment of nutritional status in end-stage renal disease
Bone biopsy and the diagnosis of renal osteodystrophy
Chronic kidney disease and coronary heart disease
Clinical manifestations and diagnosis of coronary heart disease in end-stage renal disease (dialysis)
Darbepoetin alfa for the management of anemia in chronic kidney disease
Diagnostic approach to the patient with acute kidney injury (acute renal failure) or chronic kidney disease
Epidemiology of chronic kidney disease
Erythropoietin for the anemia of chronic kidney disease among predialysis and peritoneal dialysis patients
Erythropoietin for the anemia of chronic kidney disease in hemodialysis patients
Erythropoietin: Subcutaneous administration
Hypertension following erythropoietin (EPO) in chronic kidney disease
Indications for initiation of dialysis in chronic kidney disease
Management of secondary hyperparathyroidism and mineral metabolism abnormalities in adult predialysis patients with chronic kidney disease
Management of secondary hyperparathyroidism and mineral metabolism abnormalities in dialysis patients
Overview of the management of chronic kidney disease in adults
Pathogenesis, consequences, and treatment of metabolic acidosis in chronic kidney disease
Protein restriction and progression of chronic kidney disease
Risk factors and epidemiology of coronary artery disease in end-stage renal disease (dialysis)
Secondary factors and progression of chronic kidney disease
Urinalysis in the diagnosis of kidney disease

The following organizations also provide reliable health information.

National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

National Institute of Diabetes and Digestive and Kidney Diseases

     (www.niddk.nih.gov)

National Kidney Foundation

     (800) 922-9010
     (www.kidney.org)

United Network for Organ Sharing (UNOS)

     (888) 894-6361
    (www.unos.org)

American Kidney Fund

     (www.kidneyfund.org)

American Association of Kidney Patients

     (www.aakp.org)

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Literature review current through: Oct 2014. | This topic last updated: Feb 25, 2014.
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