Kidneys: Master Chemists of the Body

Kidneys perform crucial functions that affect all parts of the body and are involved in complex operations that keep the rest of the body in balance. When the kidneys are damaged by disease, other organs are affected. Kidney problems can range from a minor urinary tract infection to progressive kidney failure. Scientific advances over the past three decades have improved our ability to diagnose and treat those who suffer from kidney disorders. Even when the kidneys no longer function, treatments such as dialysis and transplantation have brought hope and literally new life to hundreds of thousands of people.

Why are the kidneys so important?

Most people know that a major function of the kidneys is to remove waste products and excess fluid from the body. These waste products and excess fluid are removed in the urine. The production of urine involves highly complex steps of excretion and reabsorption. This process is necessary to maintain a stable balance of body chemicals.

The critical regulation of the body's salt, potassium and acid content is performed by the kidneys. The kidneys also produce hormones and vitamins that affect the function of other organs.

Where are the kidneys and how do they function?

You have two kidneys, each about the size of a fist, located on either side of the spine at the bottom of the rib cage. Each kidney contains about one million functioning units called nephrons. A nephron consists of a filtering unit of tiny blood vessels, called a glomerulus, which is attached to a tubule. When blood enters the glomerulus, it is filtered and the remaining fluid then passes through the tubule. In the tubule, chemicals and water are either added to or removed from this filtered fluid according to the body's needs. The final product is urine, which we excrete.

The kidneys perform their life-sustaining job of filtering and returning to the bloodstream about 200 quarts of fluid every 24 hours. Approximately two quarts are eliminated from the body in the form of urine, and about 198 quarts are retained in the body. The urine we excrete has been stored in the bladder anywhere from 1 to 8 hours.

What are some of the types and causes of kidney disease?

There are many types of kidney disease, and it usually affects both kidneys. If the kidneys' ability to filter the blood is damaged by disease, wastes and excess fluid may build up in the body, causing severe swelling and symptoms of kidney failure. The kidneys may be affected by diseases such as diabetes and high blood pressure. Some kidney diseases are inherited Other diseases are congenital; that is, individuals may be born with an abnormality that can affect their kidneys. The following are some of the most common types and causes of kidney disease:

  • Diabetes is the leading cause of serious kidney disease. High blood pressure (also known as hypertension) is another common cause of kidney disease.
  • Glomerulonephritis is a disease that causes inflammation of the kidney's tiny filtering units, the glomeruli.
  • Polycystic kidney disease is the most common inherited kidney disease. Kidney stones are a common kidney malady that can cause further damage to the kidneys if they are not treated. Urinary tract infections occur when bacteria enter the urinary tract and cause symptoms such as pain and/or burning during urination and more frequent need to urinate.
  • Congenital diseases such as Goodpasture's Syndrome and Reflux Disorder may also affect the kidneys. Overuse of over-the-counter medications and the use and buildup of illegal drugs in the body can cause kidney failure.


Can kidney disease be successfully treated?

Many kidney diseases can be treated successfully. Careful control of diseases like diabetes and high blood pressure can help to prevent kidney disease or slow its progression. Kidney stones and urinary tract infections often can be treated successfully. Unfortunately, the exact causes of some kidney diseases are still unknown, and specific treatments are not yet available. Sometimes these diseases progress to chronic kidney failure, requiring dialysis or kidney transplantation. Changes in diet and treatment for high blood pressure sometimes help to slow the progression of these diseases. Research is being conducted to find more effective treatment for these diseases.

How do we treat advanced kidney failure?

Treatment with hemodialysis can be performed at a dialysis unit or at home. Hemodialysis treatments are usually performed three times a week. Peritoneal dialysis generally is done at home on a daily basis. A kidney specialist can explain the different treatment options and help patients make the best treatment choices.

There has also been increasing success with kidney transplantation, either from a living donor -- who is often a family member or close friend -- or a deceased (cadaver) donor.

What are the warning signs of kidney disease?

Although many forms of kidney disease do not produce symptoms until late into the course of the disease, there are six warning signs of kidney diseases:

  1. High Blood Pressure
  2. Blood and/or protein in the urine.
  3. A creatinine blood test greater than 1.2 for women and 1.4 for men.
  4. A filtration rate (GFR) less than 60
  5. More frequent urination, particularly at night; difficult or painful urination. Puffiness around eyes, swelling of hands and feet, especially in children.

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© 2015 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.