What is chronic kidney disease (CKD)?

Chronic kidney disease develops when the kidneys permanently lose most of their ability to remove waste and maintain fluid and chemical balances inside the body. This process can develop rapidly, within 2 to 3 months, or may develop slowly over 30 to 40 years. The severity of chronic kidney disease depends on how well the kidneys are able to filter wastes from the blood ( glomerular filtration rate ).

Kidney (renal) failure caused by chronic kidney disease is almost always progressive and irreversible. The kidneys have not stopped working altogether but are not working as well as they should. You can live normally with kidneys that are not functioning at 100% or with only one functioning kidney. Dialysis or kidney transplantation is required when kidney function drops to less than 15% of normal.

Acute renal failure occurs when the kidneys suddenly stop working. It is usually caused by an event that leads to rapid kidney malfunction, such as dehydration , blood loss from major surgery or injury, or the use of certain medications, such as contrast agents used in some X-ray tests, overuse of nonsteroidal anti-inflammatory medications (NSAIDs), and the use of aminoglycoside antibiotics. For more information, see the topic Acute Renal Failure .

What causes chronic kidney disease?

The cause of chronic kidney disease is not always known. However, many conditions and diseases can damage kidneys and lead to chronic kidney disease.

• Diabetes causes about 35% of all chronic kidney disease.
• High blood pressure causes another 30%.
• Glomerulonephritis is the third most common cause of chronic kidney disease.
• Other causes include:
  • Medication use or overuse.
  • Infection and obstruction of the kidneys.
  • Inherited genetic diseases, such as polycystic kidney disease .

How will I know if I have kidney disease?

Some people with chronic kidney disease do not have any symptoms. As kidney function declines, symptoms may include:

• Fatigue.
• Frequent headaches.
• Loss of appetite (anorexia).
• Sleep problems (insomnia).
• Itchy skin.
• Frequent urination or urinary retention.
• Nausea or vomiting.
• Swelling or numbness of the hands and feet.
• Darkening of the skin.
• Muscle cramps.

What are the stages of chronic kidney disease?

Kidney disease can be divided into three stages:

• Stage 1 (decreased renal reserve): During this stage, some kidney damage is present but the remaining kidney tissue is able to do the usual work of the kidneys. The blood urea nitrogen (BUN) levels remain normal until about 75% of nephrons are destroyed. Symptoms may not be present during this stage, which can last for many years.
• Stage 2 (renal insufficiency): During this stage, the kidney can no longer completely compensate for the loss of healthy nephrons. The BUN levels begin to climb, and the glomerular filtration rate (GFR) continues to decline. The kidneys may not be able to maintain a normal fluid balance in the body. Increased urination (polyuria) and high blood pressure may be present during this stage.
• Stage 3 (uremic syndrome): During this stage, the kidneys are no longer able to remove normal amounts of urea and other waste products from the bloodstream. The BUN becomes very elevated, and low GFR levels result in low urine production and decreased urination (oliguria). Fluid retention and high blood pressure develop. Other symptoms include nausea, vomiting, confusion, and shortness of breath. This progressive loss of kidney function eventually causes death if it is not treated using dialysis or kidney transplant.

How will my doctor diagnose kidney disease?

Your doctor will use blood and urine tests to measure changing levels of chemicals in the bloodstream to help determine how well the kidneys are working. Levels of certain chemicals, such as urea and creatinine , begin to increase as kidney function declines.

Other blood tests will be used to keep track of anemia that can be caused by advanced kidney disease.

An ultrasound can measure the size of the kidneys, estimate blood flow to the kidneys, and determine whether urine flow is blocked. In some cases, a kidney biopsy may be needed to determine the cause of chronic kidney disease.

What can I expect if I have chronic kidney disease?

Chronic kidney disease is a progressive disease. In its early stages only a small part of the kidney is involved. Some people have destruction of the glomerulus ( glomerulonephritis ) or renal tubules. Early kidney disease can cause scarring, which interferes with the blood flow to a portion of the kidney ( nephrosclerosis ).

Over time, if chronic kidney disease is not treated, end-stage renal disease (ESRD) develops. When this occurs the kidneys have been severely damaged and are often replaced with nonfunctional scar tissue.

What are the complications of kidney disease?

Regardless of what causes kidney disease, problems begin to occur when the kidneys cannot adequately filter and remove waste products from the bloodstream. As levels of these waste products begin to increase, other symptoms and complications occur, including:

• Uremic syndrome.
• Anemia .
• Electrolyte imbalances .
• Fluid imbalances, causing swelling (edema).

How is kidney disease treated?

Since kidney disease is usually caused by another condition, it is treated by:

• Treating other diseases that can cause it, such as diabetes or high blood pressure .
• Preventing diseases or avoiding situations, such as medication use, that can cause kidney damage.

The goal of treatment for chronic kidney disease is to prevent or slow additional kidney damage.

Kidney dialysis or kidney transplant may be needed when end-stage renal disease (ESRD) develops.

Who can treat my kidney disease?

Many health professionals can diagnose chronic kidney disease. If chronic renal insufficiency and end-stage renal disease are present, you will probably be referred to a nephrologist.