An Introduction to the Kidneys and Chronic Kidney Disease

V.   Causes of Chronic Kidney Disease and Kidney Failure

This section outlines the most common causes of chronic kidney disease. Some people may have an increased chance of developing kidney disease. For example, you are more likely to develop kidney disease if:

Kidney disease often causes no symptoms until it reaches an advanced stage. It's important to know if you have an increased chance of developing kidney disease so you can be make sure to get checked by your doctor on a regular basis. (See Section VI for information about diagnostic tests for kidney disease.) In many cases, early diagnosis and treatment can help to slow the progression of chronic kidney disease. However, loss of kidney function may continue in some cases, eventually leading to kidney failure and the need for treatment with dialysis or a kidney transplant.

A.   Diabetes

Diabetes is a disease that occurs when your body is either unable to make insulin, or to use normal amounts of insulin properly. Insulin regulates the amount of sugar in the blood. Diabetes causes a high blood sugar level, and if uncontrolled, this eventually damages the small blood vessels in various parts of your body. When the small blood vessels of the kidneys are injured, their ability to cleanse the blood and get rid of excess fluid and waste products decreases. The chronic kidney disease caused by diabetes, called diabetic nephropathy, is the leading cause of kidney failure in the U.S. Diabetes is very common in African-Americans, Hispanic Americans, Asian Americans and American Indians, leading to a high rate of chronic kidney disease in these groups.

Diabetes can also damage the kidneys because it may cause:

Kidney failure occurs eventually in about 30 percent of people with Type 1 diabetes and in 10 to 40 percent of people with Type 2 diabetes. Type 1 diabetes usually begins in childhood, and insulin injections are required to control blood sugar. Type 2 diabetes usually occurs in people over 45, but it is becoming more common in younger people. This form of diabetes can sometimes be controlled with diet and exercise, but diabetes pills and, in some cases, insulin injections may also be needed.

If you have diabetes, the earliest sign that your kidneys may have been affected is an increased amount of protein (albumin) in your urine. A test to detect this should be done once a year. Other signs of kidney complications may include weight gain, leg and ankle swelling, leg cramps, getting up at night to urinate, and high blood pressure. If chronic kidney disease progresses, you may notice some of the symptoms listed in Section IV. You may also find that you need to use less insulin or diabetes pills.

Having diabetes does not necessarily mean your kidneys will fail. Although there are no guarantees, the following steps may help you protect yourself:

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B.   High Blood Pressure

High blood pressure is the second leading cause of kidney failure in the U.S. It occurs when blood vessels become narrowed or rigid, forcing the heart to pump harder in order to push blood through the body. In addition to causing chronic kidney disease, high blood pressure may also be a result of certain chronic kidney diseases, such as glomerulonephritis. High blood pressure is common among African-Americans, which is a major cause of their high rates of chronic kidney disease, heart disease and strokes.

High blood pressure is considered a silent disease because it usually causes no symptoms. The only way to be sure you have it is to have your blood pressure checked regularly. A variety of different diseases can cause high blood pressure, but in 90 percent of cases, no causes can be found. About 50 million Americans have high blood pressure. Those most at risk for the condition are:

If left uncontrolled, high blood pressure can damage the kidneys by causing the tiny blood vessels of the kidneys to become thickened and rigid. This reduces the blood supply, which destroys kidney tissue and significantly impairs the kidneys' ability to cleanse the blood and balance body chemicals.

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Fortunately, extensive kidney damage can be prevented if blood pressure is brought under control early. Simple lifestyle measures, such as regular exercise, weight reduction, stopping smoking and dietary changes can help to control high blood pressure and decrease the risk of kidney damage. Medications may also be needed to control blood pressure. In this case, it is very important to take your medications as prescribed by your doctor. If you have problems with a particular medication, tell your doctor. Never stop your medication without speaking to your doctor.

C.   Glomerulonephritis

Glomerulonephritis is the third leading cause of kidney failure in the U.S. This disease causes inflammation of the part of the kidney that filters the blood, the glomeruli. You may also hear this disease called nephritis, nephrosis, nephrotic syndrome, or Bright's disease. As we mentioned earlier, when the glomeruli become inflamed, the kidneys have trouble cleaning wastes and excess fluid from the blood.

Glomerulonephritis can strike anyone, but it is most common among children and young adults. A type of glomerulonephritis, called focal sclerosis, is one of the most common causes of kidney failure in children. Another common type of glomerulonephritis is called IgA nephropathy.

Glomerulonephritis may be acute or chronic. Acute glomerulonephritis usually develops suddenly, often following an infection in the throat (such as strep throat) or on the skin. The problem usually is related to a malfunction in the immune system. The antibodies produced by the body to fight the infection persist after the bacteria have been destroyed, and these antibodies begin to damage the kidneys. The main, early symptoms - which you may or may not experience - include:

You may also have the classic signs of impending kidney failure (See Section IV: Signs and Symptoms of Chronic Kidney Disease and Kidney Failure.)

In most cases, acute glomerulonephritis subsides, but chronic kidney disease develops because of kidney damage that occurred during the acute phase. Chronic glomerulonephritis is more likely to progress silently over the course of several years.

Some types of chronic glomerulonephritis run in families. Other forms of this disease are caused by changes in the immune system. Most often, however, the disease has no known cause. Sometimes, a patient will have an acute attack of glomerulonephritis, and then develop the chronic form of the disease many years later. You may not have any symptoms, but if you do, the early warning signs may include:

While there is no specific treatment for some of the chronic forms of glomerulonephritis, to help slow the progression of the disease, your doctor may tell you to:

You should also take an active part in your care by informing your doctor of any changes in your condition and by following your doctor's instructions regarding prevention of problems such as heart disease, bone disease and nerve damage.

D.   Genetic (inherited) Disorders

Inherited disorders, such as polycystic kidney disease and Alport's Syndrome, are also responsible for many cases of kidney failure in the U.S. each year. Genes are the units in your cells that carry inherited traits from parents to children. A child receives one set of genes from each parent. A genetic disease occurs when one or both parents pass abnormal genes to a child.

Sometimes, an abnormal gene from only one parent is enough to cause a disease. This is called autosomal dominant inheritance. In other cases, an abnormal gene from both parents is needed to cause disease. This is called autosomal recessive inheritance. The chance of getting an autosomal dominant disease is higher than the chance of getting a recessive disease.

1.   Polycystic Kidney Disease (PKD)

About 600,000 Americans are affected by PKD. This disease occurs about equally among men and women and in all races. Two types of PKD may occur. The adult type, which is called autosomal dominant PKD, or ADPKD, occurs when an abnormal gene is inherited from one parent. The childhood variety, which is called autosomal recessive PKD, or ARPKD, occurs when both parents pass an abnormal gene to the child. The adult form of PKD is the most common form of the disease, and it usually does not cause symptoms until the individual reaches his or her 30's or 40's.

The childhood form of PKD begins in the developing baby and is a much less common form of the disease. The severity of this type of PKD varies. Some children have kidney failure at birth while others have enough kidney function into their teens.

Polycystic kidney disease is characterized by the growth of cysts (soft, fluid filled sacs) that form in the kidney and other organs, such as the liver and pancreas. Outpouchings may also occur in the large intestine and blood vessels of the brain.

The cysts enlarge over time, and eventually, they can replace the good kidney tissue, reducing kidney function and, in some cases, leading to kidney failure. The kidneys enlarge as the cysts enlarge, and they can weigh more than 20 pounds toward the end of the process. The symptoms of PKD may include:

Not everyone who has PKD has these symptoms, and the disease can be difficult to diagnose without an ultrasound exam. It often shows up during tests for other conditions. However, if you know that the disease has affected other members of your family, you should schedule regular checkups with your doctor, even if you feel fine. Early detection is your best protection against serious complications.

If the disease is suspected, your doctor may recommend:

If cysts are not yet present, but you have a strong family history of the disease, your doctor may suggest a gene linkage analysis. In this test, several members of a family who have the disease give blood to find out whether another family member or a developing baby may be carrying the gene.

At present, no specific treatment is available for polycystic kidney disease. Regular checkups, good control of high blood pressure and prompt treatment of urinary tract infections are the best ways to slow the progress of the disease. As with other chronic kidney diseases, if kidney failure occurs, your doctor will initiate dialysis and/or recommend kidney transplantation.

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2.   Alport's Syndrome

In this inherited disease - named after A. Cecil Alport, a British doctor who first described it - the glomeruli undergo a gradual process of deterioration. The disease tends to be more severe in men than in women because of the way it is inherited. The major features of Alport's Syndrome are:

The treatment for Alport's syndrome consists of controlling high blood pressure, dietary changes and, if kidney failure occurs, dialysis or a kidney transplantation.

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E.   Congenital Disorders of the Urinary Tract

Sometimes, a defect may occur in a developing baby's urinary system. These defects can range from absence of one or both kidneys to abnormalities in the position, form, size or structure of the kidneys and other parts of the urinary system. With the use of prenatal ultrasound examinations, more of these problems are being detected and treated at an early stage.

Some of the most common congenital problems result from defects in the ureters (the tubes that carry urine from the kidneys to the bladder) or the urethra (the tube that drains urine from the bladder during urination). These defects can block the normal flow of urine, causing urine to back up, or "reflux" to the kidneys. These problems are among the more common causes of kidney failure in children. Children who have these defects may have frequent urinary tract infections with the following symptoms:

Any small child who has more than one urinary tract infection should be seen by a pediatrician or family doctor. Early diagnosis and treatment of these conditions are very important and can help prevent damage to the kidneys that can lead to high blood pressure, and in some cases, to kidney failure in later life.

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F.   Obstructions of the Urinary Tract

Obstructions, or blockages, can occur anywhere within the urinary system from the kidney itself to the ureter, bladder or urethra. Some of the causes of blockage include kidney stones, an enlarged prostate gland in men, tumors or blood clots. Even when a blockage is only partial, damage can still occur. The treatment is to correct whatever is causing the blockage.

Some common causes of blockage in the urinary system include:

1.   Kidney Stones

Kidney stones are not a major cause of kidney failure. However, recurrent kidney stones can cause damage to the kidney tissue and contribute to kidney failure. Most stones begin when a tiny particle of solid material is deposited in the middle of the kidney (where urine collects before entering the ureter). As time passes, more and more materials are added to the initial pebble until, eventually, it enlarges to become a stone.

Urinary Stones

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Also, stones often make it easier to get infections in the urinary tract. If you have repeated infections and/or scarring from kidney stones, the damage could contribute to decreased kidney function.

Kidney stones are more common in men, in younger people (20s to 40s) and in people who have a family history of kidney stone disease. The best way to protect yourself if you have kidney stones is to see your doctor regularly for check-ups, to follow any special diet recommendations, and to take any medications prescribed for you. You should call your doctor if you have any pain in the area of your kidneys. Also, get in the habit of drinking eight to 10 glasses of water a day, to help flush any small stones you have through your urinary tract, and to prevent other stones from forming.

In many cases, kidney stones pass spontaneously, without additional treatment. However, they may sometimes be too large to pass, and treatment may be needed to remove the stone. The need for open surgery to remove stones has been greatly reduced by the development of newer technologies, such as extracorporeal shock wave lithotripsy, or ESWL. This technique focuses a beam of high energy shock waves on the stone to break it down into small particles that can pass safely out of the urinary tract. Laser beams are also being used to break down kidney stones. Stones can also be removed through tube-like instruments that are inserted through the patient's side or into the lower part of the urinary tract, depending on where the stone is located.

2.   Benign Prostate Disease

The prostate is a gland that surrounds the urethra in men. As men reach their 50s and 60s, the prostate enlarges and can block the flow of urine out of the bladder. This can also cause urine to back up to the kidneys and damage kidney tissue, which could lead to reduced kidney function. The most common symptoms of benign prostate enlargement are:

Prostate enlargement can be treated with medication, or in more severe cases, with surgery. Newer treatments are being developed, including the use of lasers.

3.   Prostate Cancer

This is becoming an increasingly serious problem in older men. As the tumor enlarges, it may cause symptoms similar to benign prostate enlargement. All men should have a prostate exam as part of their yearly checkups, beginning at age 50, or earlier if they have an increased risk of developing prostate cancer (e.g., African-American men or men with a family history of the disease).

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G.   Urinary Tract Infections

Urinary tract infections occur when bacteria (germs) get into the urinary tract and cause symptoms such as pain, fever and an increased need to urinate. Usually, these infections remain in the bladder, but they sometimes spread to the kidney.

When the kidney is affected, there may be intense pain in the back, spreading forward and down, toward the groin. Other symptoms may include:

Urinary tract infections are more common in women. One possible reason for this is because women have a shorter urethra, making it easier for bacteria to gain access to the bladder. Urinary tract infections are also more common in people who have problems such as kidney stones and in men who have an enlarged prostate gland. These problems can block the normal flow of urine, and cause the urine to back up into the kidney. Unless the blockage is treated and removed, repeated infections may occur.

In most cases, urinary tract infections can be cleared up in a day or two with a combination of antibiotics and bed rest. When repeated infections occur, however, additional tests may be needed to look for the cause. Recurrent urinary tract infections may cause scarring of kidney tissue and loss of kidney function. The additional tests that may be done include blood and urine tests, X-ray studies of the kidneys, and a cystoscopy (examination of the urinary tract with a telescopic instrument). These tests help identify any underlying medical problems, and prevent long-term damage to the kidneys.

When chronic kidney infections are a problem, the doctor may prescribe low doses of antibiotics for six months or more to try to prevent recurrences. Or, in some cases, patients may be told to start taking their antibiotics as soon as they notice symptoms of an infection.

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Women with recurrent infections may also be told to follow some other steps to help prevent repeated infections. These may include:

Whenever a small child has more than one urinary tract infection, additional tests, such as an ultrasound examination, should be done to check for any blockages of urine flow. If not treated early, these problems can cause high blood pressure and chronic kidney disease later in life. (See section on Congenital Disorders.)

H.   Systemic Lupus Erythematosus (SLE)

This condition is known as an autoimmune disease. Normally, your body's immune system makes proteins, called antibodies, which protect your body against infections and foreign materials, called antigens. In an autoimmune disorder, your immune system begins to destroy your own tissues and organs because it cannot tell the difference between a foreign substance and the tissue of your body.

No one knows what causes lupus, although family history and environmental factors (e.g., infections, viruses, and toxic chemicals) may play key roles. More than a million Americans have lupus. The disease is about 10 times more common in women than in men, and is three times more common in African-Americans than in Caucasians. About a third of lupus patients develop chronic kidney disease serious enough to require treatment.

The symptoms of lupus include:

To tell whether lupus has harmed your kidneys, your doctor will probably test your urine for protein and blood. High blood levels of urea and creatinine also indicate kidney damage. Steroid medications and other drugs that suppress the body's immune system are often used to treat chronic kidney disease associated with lupus. If lupus progresses to kidney failure, patients can be treated with either dialysis or transplantation.

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I.   Drugs and Toxic Chemicals

Using large amounts of certain pain relievers may cause a risk of kidney damage called analgesic nephropathy. This is especially true for pain relievers that combine more than one active ingredient in one pill. People using these drugs for long periods should have their kidney function checked.

Some individuals have an increased risk of kidney damage caused by taking a special group of pain relievers, called nonsteroidal anti-inflammatory drugs NSAIDs). These include people who:

These people should talk to their doctors before taking NSAIDs. Some NSAIDs are available over-the-counter, including different brands of ibuprofen, ketoprofen, and naproxen sodium.

Occasionally, some antibiotics (medicines used to treat infections) may harm the kidneys. The kidneys get direct exposure to antibiotics because they are the pathway for eliminating these drugs from the body. The longer the kidneys are exposed to the drugs, and the higher the dosages, the greater the chance of possible kidney damage.

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You shouldn't be afraid to take antibiotics that have been prescribed for you, however. Using them only when your doctor feels they are necessary, and drinking plenty of fluids when you take them are the best ways to prevent any toxic effects.

Certain chemicals, drugs, or other substances can also harm the kidneys. These are called nephrotoxins. Industrial areas may be a source of environmental nephrotoxins, such as heavy metals (lead, cadmium, bismuth, arsenic, copper and mercury), carbon tetrachloride, ethylene glycol, trichloroethylene, carbon monoxide, and chlorinated hydrocarbons. Snake venom and certain mushrooms can also destroy kidney tissue.

For more information about any of the conditions described, or about other possible causes of chronic kidney disease and kidney failure, speak to your doctor.

 

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