Solitary Kidney
 

National Kidney and Urologic Diseases Information Clearinghouse 

National 

Institute of 

Diabetes and 

Digestive 

and Kidney 

Diseases 

NATIONAL 

INSTITUTES 

OF HEALTH 

U.S. Department 

of Health and 

Human Services 

Your kidneys perform many functions to keep 

you alive. They 

•	 filter wastes and extra fluid from your blood 

•	 keep the proper balance of minerals like 

sodium, phosphorus, calcium, and potassium in your blood 

•	 help maintain a healthy blood pressure 

•	 make hormones that keep your blood 

and bones healthy 

Most people have two kidneys, one on each side 

of the spinal column in the back just below the 

rib cage. Each kidney is about the size of a fist 

and contains about 1 million nephrons. The 

nephrons are microscopic filtering “baskets” 

that transfer wastes from the blood to the collecting tubules of the urinary system. 

A person may have only one kidney for one 

of three main reasons. 

•	 A person may be born with only one kidney, a condition known as renal agenesis. Renal dysplasia, another birth 

defect, makes one kidney unable to 

function. Many people with renal agenesis or renal dysplasia lead normal, 

healthy lives and only discover that they 

have one kidney—or one working kidney—when they have an x ray, sonogram, or surgery for some unrelated 

condition. 

•	 Some people must have one kidney 

removed to treat cancer or other diseases 

or injuries. The operation to remove a 

kidney is called a nephrectomy. 

•	 A growing number of people are donating a kidney to be transplanted into a 

family member or friend whose kidneys 

have failed. 

Most people can live a normal, healthy life 

with one kidney. Taking precautions is wise 

to protect the kidney function you do have. 

The kidneys remove wastes and extra water from the 

blood to form urine. Urine flows from the kidneys to the 

bladder through the ureters. 

Kidneys 

Ureters 

Bladder 

What are the possible 

effects of solitary kidney? 

If having a single kidney does affect your 

health, the changes are likely to be so small and 

happen so slowly that you won’t notice them. 

Over long periods of time, however, these 

gradual changes may require specific measures 

or treatments. Changes that may result from a 

single kidney include the following: 

•	 High blood pressure. Kidneys help 

maintain a healthy blood pressure by regulating how much fluid flows through the 

bloodstream and by making a hormone 
called renin that works with other hormones to expand or contract blood vessels. Many people who lose or donate a 

kidney are found to have slightly higher 

blood pressure after several years. 

•	 Proteinuria. Excessive protein in the 

urine, a condition known as proteinuria, 

can be a sign of kidney damage. People 

are often found to have higher-than-normal levels of protein in their urine after 

they have lived with one kidney for several years. 

•	 Reduced GFR. The glomerular filtration 

rate (GFR) shows how efficiently your 

kidneys are removing wastes from your 

bloodstream. People have a reduced 

GFR if they have only one kidney. 

Blood with 

wastes 

Clean blood 

Glomerulus 

Nephron 

Tubule 

Wastes (urine) 

to the bladder 

In the nephron (left), tiny blood vessels 

intertwine with urine-collecting tubes. 

Each kidney contains about 1 million 

nephrons. 

You can have high blood pressure, proteinuria, and reduced GFR and still feel fine. 

As long as these conditions are under control, 

they will probably not affect your health or 

longevity. Schedule regular checkups with 

your doctor to monitor these conditions. 

How can you protect 

your kidneys? 

Monitoring 

Your doctor should monitor your kidney 

function by checking your blood pressure and 

testing your urine and blood once a year. 

•	 Normal blood pressure is considered to 

be 120/80 or lower. You have high blood 

pressure if it is over 140/90. People with 

kidney disease or one kidney should 

keep their blood pressure below 130/80. 

Controlling blood pressure is especially 

important because high blood pressure 

can damage kidneys. 

•	 Your doctor may use a strip of special 

paper dipped into a little cup of your 

urine to test for protein. The color of 

the “dipstick” indicates the presence or 

absence of protein. A more sensitive 

test for proteinuria involves laboratory 

measurement and calculation of the 

protein-to-creatinine ratio. A high 

protein-to-creatinine ratio in urine 

(greater than 30 milligrams of albumin 

per 1 gram of creatinine) shows that kidneys are leaking protein that should be 

kept in the blood. 

•	 Measuring GFR used to require an injection of a contrast medium like iothalamate into the bloodstream followed by a 

24-hour urine collection to see how much 

of the medium is filtered through the kidneys in that time. In recent years, however, scientists have discovered that they 

can estimate a person’s GFR based on 

the amount of creatinine in a small blood 

sample. The new GFR calculation uses 

the patient’s creatinine measurement 

along with weight, age, and values 

assigned for sex and race. Some medical 

laboratories may calculate GFR at the 

same time they measure and report creatinine values. If your GFR stays consistently below 60, you are considered to 

have chronic kidney disease. 

2 Solitary Kidney 
Controlling Blood Pressure 

If your blood pressure is above normal, you 

should work with your doctor to keep it below 

130/80. Great care should be taken in selecting blood pressure medicines for people with 

a solitary kidney. Angiotensin-converting 

enzyme (ACE) inhibitors and angiotensin 

receptor blockers (ARBs) are two classes of 

blood pressure medicine that protect kidney 

function and reduce proteinuria. But these 

medicines may be harmful to someone with 

renal artery stenosis (RAS), which is the narrowing of the arteries that enter the kidneys. 

Diuretics can help control blood pressure by 

removing excess fluid in the body. Controlling your blood pressure may require a combination of two or more medicines, plus 

changes in diet and activity level. 

Eating Sensibly 

Having a single kidney does not mean that you 

have to follow a special diet. You simply need 

to make healthy choices, including fruits, vegetables, grains, and low-fat dairy foods. Limit 

your daily salt (sodium) intake to 2,000 milligrams or less if you already have high blood 

pressure. Reading nutrition labels on packaged foods to learn how much sodium is in one 

serving and keeping a sodium diary can help. 

Limit alcohol and caffeine intake as well. 

Avoid high-protein diets. Protein breaks 

down into the waste materials that the kidneys must remove, so excessive protein puts 

an extra burden on the kidneys. Eating moderate amounts of protein is still important for 

proper nutrition. A dietitian can help you 

find the right amount of protein in your diet. 

Avoiding Injury 

Some doctors may advise patients with a solitary 

kidney to avoid contact sports like boxing, football, and hockey. One study indicated that 

motor vehicle collisions and bike riding accidents 

were more likely than sports injuries to seriously 

damage the kidneys. In recent years, athletes 

with a single working kidney have participated in 

sports competition at the highest levels. Having 

a solitary kidney should not automatically disqualify you from sports participation. Children 

should be encouraged to engage in some form of 

physical activity, even if contact sports are ruled 

out. Protective gear such as padded vests worn 

under a uniform can make limited contact sports 

like basketball or soccer safe. Doctors, parents, 

and patients should consider the risks of any 

activity and decide whether the benefits outweigh those risks. 

Hope Through Research 

In recent years, researchers have learned 

much about kidney disease. The National 

Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsors several programs aimed at understanding kidney failure 

and finding treatments to stop its progression. The NIDDK’s Division of Kidney, Urologic, and Hematologic Diseases supports 

basic research into normal kidney development in the embryo and the genetic causes of 

birth defects that may result in a solitary kidney. New imaging techniques can help to 

diagnose solitary kidney before birth. 

For More Information 

American Association of Kidney Patients 

3505 East Frontage Road, Suite 315 

Tampa, FL 33607 

Phone: 1–800–749–2257 or 813–636–8100 

Email: info@aakp.org 

Internet: www.aakp.org 

American Kidney Fund 

6110 Executive Boulevard, Suite 1010 

Rockville, MD 20852 

Phone: 1–800–638–8299 or 301–881–3052 

Email: helpline@kidneyfund.org 

Internet: www.kidneyfund.org 

Life Options Rehabilitation 

Resource Center 

c/o Medical Education Institute Inc. 

414 D’Onofrio Drive, Suite 200 

Madison, WI 53719 

Phone: 1–800–468–7777 

Email: lifeoptions@meiresearch.org 

Internet: www.lifeoptions.org 

www.kidneyschool.org 

3 Solitary Kidney 
National Kidney Foundation 

30 East 33rd Street, Suite 1100 

New York, NY 10016 

Phone: 1–800–622–9010 or 212–889–2210 

Internet: www.kidney.org 

National Kidney and 

Urologic Diseases 

Information Clearinghouse 

3 Information Way 

Bethesda, MD 20892–3580 

Phone: 1–800–891–5390 

Fax: 703–738–4929 

Email: nkudic@info.niddk.nih.gov 

Internet: www.kidney.niddk.nih.gov 

The National Kidney and Urologic Diseases 

Information Clearinghouse (NKUDIC) is a 

service of the National Institute of Diabetes 

and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National 

Institutes of Health of the U.S. Department 

of Health and Human Services. Established 

in 1987, the Clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic 

disorders and to their families, health care 

professionals, and the public. The NKUDIC 

answers inquiries, develops and distributes 

publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about 

kidney and urologic diseases. 

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This publication 

was originally reviewed by Akinlolu Ojo, 

M.D., Ph.D., University of Michigan. 

You may also find additional information on this 

topic using the following databases: 

The NIDDK Reference Collection is a collection of thousands of materials produced for 

patients and health care professionals, including 

fact sheets, brochures, and audiovisual materials. Visit www.catalog.niddk.nih.gov/resources. 

MedlinePlus brings together a wealth of information from the National Library of Medicine, 

the National Institutes of Health, and other government agencies and health-related organizations. MedlinePlus offers easy access to medical 

journal articles, a medical dictionary and medical encyclopedia, health information in Spanish, 

hospital and physician directories, drug and supplement lists, interactive patient tutorials, links 

to hundreds of clinical trials, and the latest 

health news. Visit www.medlineplus.gov. 

This publication is not copyrighted. The Clearinghouse encourages users of this fact sheet to 

duplicate and distribute as many copies as 

desired. 

This fact sheet is also available at 

www.kidney.niddk.nih.gov. 

This publication may contain information about 

medications used to treat a health condition. 

When this fact sheet was prepared, the NIDDK 

included the most current information available. 

Occasionally, new information about medication 

is released. For updates or for questions about 

any medications, please contact the U.S. Food 

and Drug Administration at 1–888–INFO–FDA 

(463–6332), a toll-free call, or visit their website 

at www.fda.gov. Consult your doctor for more 

information. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 07–5390 

July 2007