How common is it to have just one kidney?

It is not unusual for people to have only one kidney to do the work that two kidneys ordinarily do. Many people are born with a single kidney - this occurs in about one out of 750 people. This is not usually due to a particular disease or an illness, it is just a variation of nature. Being born with a single kidney is more common in males, and the left kidney is more often absent.

A kidney may need to be removed surgically because of a medical condition such as obstruction, tumours, severe trauma or an accident. This leaves the person with a single remaining healthy kidney. Regular consultation may be necessary to monitor the health of the remaining kidney.

Other people may have a single kidney because they have generously donated one of their kidneys to a compatible family member or close friend who has suffered kidney failure. People with kidney failure must undergo regular dialysis treatment or receive a kidney transplant in order to survive. Should a person choose to donate, they must undergo a series of tests to ensure it is suitable and safe to do so. Their kidney health will also be monitored over time.

A single kidney will grow faster and larger than a normal kidney. For this reason, people with this condition usually have entirely normal kidney function when measured. The increased growth of the single kidney assists in compensating for the absence of the function of a second kidney.

What about playing contact sport?

If you only have one kidney, it is important to be aware of the risk of injury with certain heavy contact sports that involve direct blows to the kidney (eg. kick-boxing, karate). In deciding whether to participate in such sports, the consequences of losing a single kidney should be considered carefully. You may wish to consult with your doctor before participating, to help evaluate the risks.

In the long-term, there are no problems associated with having only one healthy kidney. There are no special precautions needed for child-bearing, and special diets are generally not required for those with a single healthy kidney. A low fat, high fibre diet and drinking at least two litres of water a day are recommended for everyone as part of a normal healthy diet.

Notify your doctor

If you have only one healthy kidney, it is not necessary to have special visits to the doctor. If you have a new doctor, notify them that you have a single kidney to ensure they are aware of your circumstances. Like most of us, people with a single kidney should have a check-up once a year, including a blood pressure test and urine analysis.

If there is any indication that the single kidney is abnormal, a doctor or specialist will be able to determine whether there are any special precautions that need to be observed.

Original material provided by the New Zealand Kidney Foundation. Edited by everybody, August 2005.