The kidneys are 2 bean-shaped organs that are located toward your back, on either side of your spine, just underneath the rib cage. A kidney is about as big as a fist.
The kidneys do several things. They are responsible for making urine by filtering wastes and extra water out of the body. The kidneys also produce certain necessary hormones (erythropoietin, renin, and calcitriol) and help to regulate blood pressure by producing life-sustaining chemicals. During 1 day, the kidneys clean out 200 quarts of blood.
In each kidney, there are about 1 million nephrons. These small nephrons are the kidney parts that do the cleaning. A nephron has a glomerulus, which is a small blood vessel, and a tubule, which collects urine.
Kidney function, also called renal function, describes how well the kidneys work. If a person has 2 healthy kidneys, he or she is said to have 100% kidney function. If the kidneys lose even 30% to 40% of function, one might not even notice. A person can live with just 1 healthy kidney. However, when kidney function falls below 25%, serious problems develop. A person with less than 10% to 15% kidney function will need to have treatment to replace kidney function. The treatment choices are dialysis, a process to cleanse the blood and body, or a kidney transplant.
Kidney transplantation involves placing a healthy kidney into the body where it can perform all of the functions that a failing kidney cannot. Kidneys for transplantation come from 2 sources: living donors and deceased (non-living) donors. Living donors are usually immediate family members or sometimes spouses. This is possible because a person can live well with one healthy kidney.
Deceased donor kidneys usually come from people who have willed their kidneys before their death by signing organ donor cards. All donors are carefully screened to make sure there is a suitable match and to prevent any transmissible diseases or other complications.
Kidney diseases occur when the nephrons are damaged and cannot filter the blood. The damage can happen quickly, such as when it is caused by injury or toxins. However, most damage occurs over a period of time. High blood pressure (hypertension) and diabetes are the 2 most common causes of the progressive type of damage to the nephrons and the resulting kidney failure (chronic kidney disease or CKD). CKD is also known as chronic renal insufficiency.
In the early stages, there usually are no symptoms. As the disease worsens, symptoms may include:
Often, kidney diseases are discovered through routine testing of blood or urine. According to the National Kidney Foundation, 3 tests are recommended for testing for kidney disease:
In addition, measuring the level of urea nitrogen in the blood can also be useful.
If these tests come back with an indication of kidney disease, your health care provider may order additional testing. These may include imaging tests, such as ultrasound, magnetic resonance imaging (MRI), and computerized tomography (CT) scans. If the healthcare provider needs additional information, he or she may order a kidney biopsy. This procedure means that a needle is used to retrieve a piece of kidney tissue in an operation using local anesthesia.
There is no cure for chronic kidney disease, but steps may be taken in early CKD to preserve a higher level of kidney function for a longer period of time. People who have reduced kidney function should:
Because there is no cure for CKD, people who are in the later stages of the disease must consider options. Complete kidney failure, left untreated, will result in death. Options for patients in the end stages of CKD include dialysis and kidney transplantation.
Dialysis is a procedure that uses machines to remove waste from the body when the kidneys are no longer able to perform this function. There are 2 major types of dialysis.
The hemodialysis machine has a dialyzer to clean the blood of waste products, excess water, and excess salt. The blood is then returned to the body. Hemodialysis is performed for 3 to 4 hours 3 times a week. This is done primarily at a clinic or hospital, but efforts are being made to implement home hemodialysis treatments.
In peritoneal dialysis, the dialysis solution is introduced into the patient’s abdomen. The solution captures waste and then is removed via catheter. Fresh solution is added to continue the process of cleaning. This type of dialysis can be performed by the patients themselves. There are 2 types of peritoneal dialysis: continuous ambulatory peritoneal dialysis (CAPD), which involves a change in dialysis solution 4 times per day; and continuous cycling peritoneal dialysis (CCPD). The latter procedure uses a machine to automatically fill, remove wastes, and refill the fluid during the nighttime.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 09/22/2015