Health Library

Kidney Disease

The kidneys are a pair of hardworking little organs. They clear the waste products out of our blood stream. Located just below the rib cage near the middle of your back, they filter about 200 quarts of blood a day to extract about 2 quarts of waste and extra water. It becomes urine and is stored in your bladder until you go the bathroom. This whole thing takes place in what are called nephrons, where the blood carrying capillaries intertwine with the urine carrying tubules.

The kidneys are part of your urinary system. (Read about "The Urinary System") They also regulate a number of chemicals in our blood stream and release hormones such as:

• active form of vitamin D to help regulate the calcium (Read about "Calcium" "Vitamins & Minerals") in our blood for bone building (Read about "Skeletal System")
• renin which helps regulate blood pressure
• erythropoietin or EPO which helps the bone marrow make red blood cells

The kidneys are crucial to our survival, but believe it or not we don't need both of them. There are people who are born with one kidney (Read about "Genitourinary Birth Defects"), or who donate one to another person, who live normal and active lives. However, as the percentage of your kidneys' abilities drops, you start having problems.

Signs and symptoms of kidney disease

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists the following as some of the signs and symptoms of kidney disease:

• frequent headaches or tiredness
• itchy all over your body
• more or less than normal urination
• hematuria or blood in the urine
• urine that appears pink
• urine that appears foamy
• edema or swelling in the hands and feet or numbness (Read about edema in "Feet, Ankles and Legs")
• loss of appetite
• nausea and vomiting
• trouble concentrating
• drowsiness
• darkening skin
• muscle cramps (Read about cramps in "Feet, Ankles and Legs")

Kidney failure

Renal (kidney) failure results when the kidneys are not able to regulate water and chemicals in the body or remove waste products from your blood.

Acute renal failure (ARF) is the sudden onset of kidney failure. This condition can be caused by an accident that injures the kidneys, loss of a lot of blood or some drugs or poisons. Hemolytic uremic syndrome (HUS) is one of the most common causes of sudden, short-term kidney failure in children. Most cases of HUS occur after an infection of the digestive system by Escherichia coli (E. coli) bacterium. (Read about "E. coli") ARF may lead to permanent loss of kidney function. But if the kidneys are not seriously damaged, they may recover.

Chronic kidney disease (CKD) is the gradual reduction of kidney function. You may go several years without knowing you have chronic kidney disease. This is dangerous, because chronic kidney disease may lead to end-stage renal disease or ESRD. ESRD is the loss of 85 to 90 percent of your kidney function. This means that your kidney function is so low that the complications can be severe, even fatal, without dialysis or kidney transplantation. (Read about "End Stage Renal Disease" "Transplants")

Kidney failure can result from a number of conditions including

• hypertension or high blood pressure (Read about "Hypertension: High Blood Pressure")
• diabetes (Read about "Diabetes" "Diabetes and Kidney Disease")
• lupus (Read about "Lupus")
• glomerular diseases, which are diseases that attack the tiny blood vessels (glomeruli) within the kidney.
• polycystic kidney disease (Read about "Polycystic Kidney Disease")
• certain medications, including over-the-counter painkillers, may cause kidney damage if taken over long periods of time. Ask your doctor if this should be a concern for you. (Read about "Medicine Safety")

Kidney failure can also be a cause of high blood pressure, as well as bone loss. (Read about "Blood Pressure and Kidney Disease "Bone Loss and Kidney Disease")

Anemia is also common in people with kidney failure, according to NIDDK. This is because diseased kidneys often don't make enough EPO, which stimulates the bone marrow to produce red blood cells. Red blood cells are needed to carry oxygen to vital organs. With a fewer red blood cells, anemia develops. (Read about "Anemia")

Other kidney problems

In addition to kidney failure, there are a number of other things that can go wrong with the kidneys:

Kidney stones are a painful condition where a small stone forms in the kidney and will occasionally move down through the urinary system. Half a million people are estimated to get kidney stones every year by NKF. (Read about "Kidney Stones")

Cysts are also known to form in the kidney but they seldom cause problems. Cysts in the kidney are usually small round sacs filled with watery fluid. The American Academy of Family Physicians (AAFP) says up to 50 percent of people over 50 years of age have cysts in their kidneys. They are almost always benign or non-cancerous. They usually don't cause any problems. In fact, many people have them and don't even know it. This is a different situation than polycystic kidney disease (PKD) and acquired cystic kidney disease (ACKD) which are characterized by the growth of numerous cysts in the kidneys. (Read about "Polycystic Kidney Disease")

Tumors and cancer can also develop in the kidneys. Although kidney cancer is far more common in adults, some forms of kidney cancer, such as Wilms' tumor, can affect children. (Read about "Kidney Cancer")

Infections can affect the kidneys. If the infection is in one or both of the kidneys, the infection is called pyelonephritis. This type of urinary tract infection UTI can cause serious damage to the kidneys if it is not adequately treated. (Read about "Urinary Tract Infections")

Testing for kidney disease

Many people discover they have kidney disease from a blood or urine test. Protein is a major building block that our body uses to build muscle. Normally the kidneys leave protein in the blood. If protein shows up in your urine, it indicates problems with the kidneys. It's called proteinuria.

Your blood can also be checked for excess levels of urea and creatinine, which are normal waste products. Excess levels in the blood indicate reduced kidney function and are a warning sign for your doctor. Your glomerular filtration rate (GFR) is a measure of how well your kidneys are filtering wastes from your blood. Your GFR can be estimated from a routine measurement of creatinine in your blood.

Cystoscopy lets the doctor examine the urinary tract by inserting a thin tube through the urethra. (Read about "Endoscopy") On the end of the tube are special optics that let the doctor see the urethra, bladder and kidneys. Small samples of tissue may also be removed during this examination.

Renal imaging procedures, such as ultrasound, CT scan or MRI of the kidneys (Read about "Ultrasound Imaging" "CT Scan - Computerized Tomography" "MRI - Magnetic Resonance Imaging"), are also used to check the kidneys for growths such as stones or cysts.

Your doctor may also recommend a kidney biopsy. This is a procedure in which a needle is used to extract small pieces of tissue for examination with different types of microscopes, each of which shows a different aspect of the tissue. (Read about "Biopsy")

Treatment

Treatment varies depending on the reasons for the kidney problems. There is no way to reverse kidney damage, according to NIDDK, but you can slow it down, getting treatment for whatever is causing the damage. If you have diabetes, it is essential that you keep your blood sugar levels under control. If you have hypertension, it is important that you treat this condition with diet, exercise and/or medication. Treatments for glomerular diseases may include immunosuppressive drugs or steroids to reduce inflammation and proteinuria, depending on the specific disease. Because the kidneys are so crucial, it is imperative that you consult with your doctor about treatments and follow the doctor's directions carefully.

For more information on kidney and urinary tract problems, see the conditions listed below:

    Incontinence

    Cystitis

    Urinary Tract Infection

    Kidney Stones

    Kidney Cancer

    Bladder Cancer

    Polycystic Kidney Disease

    End Stage Renal Disease

    Diabetes and Kidney Disease

    Blood Pressure and Kidney Disease

    Bone Loss and Kidney Disease