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One kidney (a solitary kidney): the checkups, keeping it safe, and giving a kidney
For anyone born with one kidney, who had one removed, who gave one to someone, or who was just told they have only one, and for the parents of a child with one. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of the NIH) says that if you have only one kidney, that kidney is called a solitary kidney, and that complications are rare. This page passes on, by name, what NIDDK says: what it is and the three main causes; what it can lead to; the urine, blood and blood pressure checkups; telling every provider, pain relievers, and sports; and food, pregnancy, and giving a kidney. It builds the words to say and the questions to ask, and prints a card to keep in your wallet.
A word with a dotted line under it, like this, opens its official definition, quoted from a U.S. government glossary.
Right now
- Trouble breathing, chest pain, or fainting? Call 911 (ours).
- A hit to the belly, side or back, and now pain that does not go away, blood in the urine, or you cannot pee? Get care right away; if you cannot reach your provider, go to the emergency room, and say you have one kidney (ours).
- About to take a new medicine or have a procedure? Tell them you have one kidney; NIDDK says to, to prevent injury from medicines or procedures.
- Worn down, or thinking of ending your life? Call or text 988, any hour (ours).
More help
- The kidneys, on this site: Kidney disease · Kidneys, bladder and urine: find the right page · Blood in the urine.
- Tests: Urinary tract imaging · Medical tests: find the right page.
- Related: High blood pressure · Sports injuries · Pregnancy and a new baby.
- Getting ready: My medicines list · Get ready for your appointment.
- Care and costs: When you need a doctor and can’t pay · Medical bills.
- In a crisis: Help right now (988, 911). All our free tools.
Kidneys, bladder or urine, and not sure this is the right page? The pages on this site for bladder infections, kidney stones, blood in the urine, bladder pain, bladder leaks, the prostate, kidney disease and bedwetting, on one list.
Other guides on this site that go with this page
Free to read. We chose these ourselves; no professional did. Each guide was written with AI and has not been reviewed by a professional. They are general information, not advice.
- Kidney failure: choosing a treatment (dialysis, a transplant, or conservative care): kidney failure (kidneys failing or about to fail; choosing between hemodialysis, peritoneal dialysis, a kidney transplant, or conservative management, care without dialysis): the signs and when to start, how to choose and change your mind, an advance directive, dialysis at a center or at home, the access, infection signs, the transplant waiting list and living donors, food by treatment, work, and paying for it (Medicare, Medicaid, the social worker).
- Nephrotic syndrome: in adults and in children: nephrotic syndrome in adults and in children (swelling, foamy urine, protein in the urine): what causes it, the signs and what it can lead to, the urine and blood tests, the treatment, and steroids and relapses in children.
- Glomerular disease: the signs, the causes, the tests, and the treatment: glomerular disease (FSGS, lupus nephritis, membranous nephropathy, minimal change disease and others; foamy or cola-colored urine, swelling, or a kidney biopsy that showed it): what it is, the causes and who gets it, the signs and what it can lead to, the tests and the biopsy, the kinds of medicine and kidney failure, and food, family and research.
- IgA nephropathy (Berger’s disease): the signs, the biopsy, and the treatment: IgA nephropathy, Berger’s disease (pink, cola-colored or foamy urine, swelling, or a kidney biopsy that showed it): what it is, who is more likely to have it, the signs and what it can lead to, the tests and the biopsy, the kinds of medicine and less salt, and food, family and research.
- Polycystic kidney disease (PKD): the types, the signs, the tests, and slowing it down: polycystic kidney disease (PKD; many fluid-filled cysts in the kidneys, often in the family; pain in the back or sides, headaches, high blood pressure, blood in the urine): what it is, the two types (ADPKD in adults, ARPKD in babies) and the genes, the signs and what it can lead to (kidney failure, brain aneurysms, liver cysts), the imaging and genetic tests and genetic counseling, pain medicine and the kidneys, a blood pressure goal, the steps that may slow it, food and drink, and the costs.
- Kidney disease in children: the signs, the causes, the treatment, and school: kidney disease in a child (acute kidney injury or chronic kidney disease; swelling, foamy or pink urine, peeing more or less, or wetting the bed again): what it is, which children get it and the causes, the signs and what it can lead to, the tests and the kidney doctor for children, the kinds of medicine, dialysis and transplant, and school (an IEP or a 504 plan), friends and feelings.
- Kidney stones: the signs, when it is an emergency, passing a stone, and preventing the next one: kidney stones: the signs, when it is an emergency, passing a stone, and preventing the next one.
- Simple kidney cysts: what they are, the symptoms, the tests, and when they need treatment: simple kidney cysts (fluid-filled sacs in the kidneys, often found by chance on a scan): what they are, how common, the rare problems, the scans and lab tests, watching, draining, surgery, and how they differ from PKD.
- How the kidneys work: where they are, what they do, the nephrons, and how blood flows through them: how the kidneys work (where they are, what they do, the nephrons, the glomerulus and the tubule, and how blood flows through them): the wastes, the balance of water, salts and minerals, the hormones, the numbers in a day, and the words in plain language.
- Ectopic kidney: what it is, the problems it can cause, the tests, and the treatment: an ectopic kidney (a kidney out of its usual place: a pelvic kidney, crossed renal ectopia), often found by chance or on an ultrasound in pregnancy: what it is, what causes it, how common it is, the problems it can cause (reflux, blockage, infections, kidney stones, injury), the symptoms, the tests, the treatment, and living with one working kidney.
- Multicystic dysplastic kidney (MCDK): what it is, the problems it can cause, how it is found, and the checkups: a multicystic dysplastic kidney (MCDK: a baby’s kidney filled with cysts that does not work), most often seen on an ultrasound in pregnancy: what it is, what causes it, how common it is, the problems it can cause (high blood pressure, the working kidney), the symptoms, how it is found, the treatment and the checkups, and food.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 18, 2026 on NIDDK’s (NIH) page Solitary or Single-functioning Kidney (last reviewed October 2020), with the lines on living donors from its Kidney Transplant page (January 2018) and the lines on pain relievers and the pharmacy from its Keeping Kidneys Safe: Smart Choices about Medicines page (June 2018), which was written for people with kidney disease, diabetes or high blood pressure. The first two pages are in Spanish too; the third is in English only, so our Spanish page translates those lines with AI. The numbers (about 1 in 2,000 babies born with kidney agenesis; between 1 in 1,000 and 1 in 4,300 with kidney dysplasia; more than 58,000 living donors and more than 255,000 kidneys removed for cancer between 2008 and 2017; 2 to 3 days in the hospital with the smaller-cut technique; Medicare for 3 years after a transplant) are NIDDK’s. Ours: 911 for trouble breathing, chest pain, or fainting; getting care right away after a hit to the belly, side or back with pain, blood in the urine, or no urine; asking whether the medicines page applies to you; telling every provider about procedures and scans with contrast dye; telling the pregnancy care team, the school and the coach; never stopping a prescribed medicine on your own; asking the transplant center what is covered; 988 when it is too much; health centers when money is tight; and the order of the steps. What we left out: the clinical trials sections, the references, the rest of the kidney transplant page (it is for the person receiving a kidney), the medicine examples on the medicines page, and NIDDK’s outside links. This page saves nothing and loads no trackers.