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Patient Education and Resources

Your Kidneys

Your kidneys are twin organs located in the back on either side of the spine, protected by the lower ribs. Each kidney is about the size of a fist and weighs approximately five ounces. Although most people have two kidneys, odds are that one in every 500 healthy babies is born with just one. You need only one healthy kidney to live normally.

Filtering Blood

The heart brings blood to the kidneys through large blood vessels called arteries. The kidneys filter your blood as it passes through, and remove wastes and excess salts, minerals, and fluid from the circulation. After it is filtered, the cleansed blood returns to the heart through large blood vessels called veins. From there, the blood circulates throughout the body. By filtering and cleansing your blood, the kidneys maintain the normal amounts of wastes, salts, minerals, and fluid in the body.

Urine Production

Your kidneys produce urine from the wastes and fluids they remove from the blood. Here is how urination works:

  • Ureters, two long hollow tubes that connect each kidney to the bladder, drain the urine the kidneys produce into the bladder.
  • The bladder, located in the lower part of the abdomen, is a sac-like structure that stores the urine until it becomes full, at which time it resembles a water balloon (although the bladder wall is thicker due to muscles in the wall of the bladder that help it contract and empty as you urinate. See below).
  • When your bladder is full, you feel the urge to urinate.
  • Urination begins when a muscle at the neck of the bladder relaxes and opens a valve to the urethra. Muscles in the wall of the bladder contract and help force the urine into the urethra.
  • The urethra is one short, hollow tube, which drains urine from the bladder out through the opening at the tip of the penis in men, or just above the vagina in women.

Producing Hormones

The second major function of the kidneys is to produce hormones, vital to good health. These hormones regulate blood pressure, stimulate production of red blood cells in the bone marrow, and help the bones stay strong by increasing the amount of calcium absorbed from food.

Kidney Failure: Acute and Chronic

Kidney failure occurs when kidneys do not perform as they should. Acute kidney failure is when kidneys stop functioning temporarily or suddenly. Chronic kidney failure is when kidneys slowly lose function over several years, often resulting in permanent kidney failure. Both kidneys usually fail at the same rate.

Many different diseases can harm kidneys and cause them to fail. Some of these diseases work quickly - in just days or weeks - while others take years to do damage. The most common cause of kidney failure in the United States is diabetes mellitus. Hypertension (long-standing high blood pressure) or malignant hypertension (severe high blood pressure) can also lead to kidney failure.

Kidney Problems

  • If your kidneys do not maintain the correct balance of chemicals and minerals in your blood, an imbalance may occur that can impact the ability of other organs to function properly.
  • If your kidneys produce too much of a particular hormone, you may develop high blood pressure.
  • If your kidneys produce too little of a particular hormone, you may become anemic (your blood does not produce enough red blood cells).


Signs and symptoms of kidney failure include:

  • Fatigue
  • Difficulty sleeping
  • Dry, itchy skin
  • Vomiting and nausea
  • Confused thinking
  • Extra fluid retention
  • Metallic taste in the mouth


There are two treatments for end-stage kidney failure: dialysis and transplant. When kidneys fail, patients need one of these treatments in order to survive.


Dialysis replaces kidney function by using special equipment to clean wastes from the blood. There are two forms of dialysis:

  • Hemodialysis circulates blood through a machine outside of the body to remove toxins and excess fluid and to correct electrolytes like potassium, sodium, phosphate and calcium, to name a few. The machine then pumps the cleansed blood back into the body. This type of dialysis usually involves going to a dialysis center three times each week, but can sometimes be done at home.
  • Peritoneal Dialysis, using the lining of the abdominal cavity as a filter, purifies blood by flushing the abdominal cavity with a diluted salt solution. The solution traps wastes and is usually drained from the abdomen through a catheter, which is a surgically placed tube. This type of dialysis can be done at home or at work, although people who have had abdominal surgery are not the best candidates for this procedure. Scar tissue in the abdomen can prohibit an adequate amount of fluid from being instilled into the peritoneal cavity and interfere with dialysis effectiveness.

Hemodialysis or peritoneal dialysis eliminate most wastes and excess chemicals from your blood if your kidneys are not doing so on their own. However, dialysis cannot replace all the filtering functions of the kidney or the hormone production the kidneys normally generate. People on dialysis often need medication therapy to help correct anemia.

Dialysis Access

Dialysis access is the surgical process of establishing a vascular connection between the patient's bloodstream and an artificial kidney (the dialysis machine). Surgeons create vascular access in the arm or leg for hemodialysis or in the abdomen for peritoneal dialysis. Complications associated with long-term dialysis include infection, bleeding, swelling and blockage of flow through the dialysis access.

Dialysis Access Center

The Transplant Institute has a Dialysis Access Center to provide prompt, state-of-the-art care to patients who need to have a dialysis access created or repaired before undergoing hemodialysis or peritoneal dialysis.

Kidney Transplantation

While dialysis is a life-saving treatment, it does only about 10 percent of the work that a functioning kidney does. Because of its impact on the body, dialysis can also cause other health problems for patients. The typical patient will live 10 to 15 years longer with a kidney transplant than if he or she stayed on dialysis. And most people report that in comparison, transplantation offers them a much better quality of life.

Contact Information

Transplant Institute
Beth Israel Deaconess Medical Center
Lowry Medical Office Building, 7th Floor
110 Francis Street
Boston, MA 02215