What your kidneys do, and what chronic kidney disease means
MedlinePlus explains that you have two kidneys, each about the size of your fist, and that their main job is to filter your blood. They remove wastes and extra water, which become urine. They also keep the body's chemicals balanced, help control blood pressure, and make hormones.
NIDDK describes chronic kidney disease, also called CKD, as a condition in which your kidneys are damaged or have a problem with their structure that prevents them from filtering blood the way they should. As a result, waste and extra fluid can build up in your body. CKD often develops slowly over many years, though sometimes it can develop after a sudden event.
CKD is common. NIDDK reports that researchers estimate more than 35 million U.S. adults, more than 1 in every 7 adults, have CKD. MedlinePlus adds that diabetes and high blood pressure are the most common causes, and NIDDK lists diabetes, high blood pressure, heart and blood vessel disease, and a family history of kidney disease as key risk factors, with risk increasing with age.
A condition that usually has no early symptoms
NIDDK states that most people in the early stages of CKD do not have symptoms, and many people have no symptoms until their kidney disease is advanced. For many people, the only way to know if they have CKD is to get their kidneys checked with blood and urine tests. MedlinePlus makes the same point on its kidney tests page: early kidney disease usually does not have signs or symptoms, and testing is the only way to know how your kidneys are doing.
People with CKD may get swelling, called edema, which can happen when the kidneys cannot remove extra fluid and salt from the body. Edema can occur in the legs, feet, ankles, or less often in the hands or face, and is more common when kidney disease is very advanced or when there is a lot of protein leaking into the urine.
As CKD becomes more advanced, symptoms may include loss of appetite, nausea or vomiting, feeling tired or having sleep problems, trouble concentrating, a change in how often you urinate, foamy urine, itching or dry or darkened skin, muscle cramps, or chest pain or shortness of breath. These later signs are reasons to talk with a clinician promptly, not a basis for self-diagnosis.
The tests that check kidney health
MedlinePlus describes kidney tests as checking how well your kidneys are working, and notes they include blood, urine, and imaging tests. The glomerular filtration rate, or GFR, is one of the most common blood tests to check for chronic kidney disease, and it tells how well your kidneys are filtering. Creatinine blood and urine tests check levels of creatinine, a waste product that your kidneys remove from your blood. An albumin urine test checks for albumin, a protein that can pass into the urine if the kidneys are damaged.
Imaging tests such as an ultrasound provide pictures of the kidneys so a health care provider can see their size and shape and check for anything unusual, and in some cases a kidney biopsy is used to check the cause of kidney disease and how damaged the kidneys are. Creatinine and other kidney-related numbers often appear in a basic metabolic panel, which our guide to common lab tests in medical weight care explains in plain language.
MedlinePlus recommends getting checked for kidney disease if you have the key risk factors: diabetes, high blood pressure, heart disease, or a family history of kidney failure. As with any lab number, interpretation belongs to the clinician who ordered the test, not to a result read in isolation.
Why kidneys come up in weight-care conversations
The conditions that most often lead to kidney disease, diabetes, high blood pressure, and heart disease, are the same ones that often come up in a weight-care intake. That is why a weight-care clinician will usually ask about kidney history, past creatinine or GFR results, and your full medicine list. Our guides to prediabetes and high blood pressure cover the two most common causes in detail.
A kidney finding is context, not a disqualifier. NIDDK explains that managing blood pressure, blood glucose levels, and weight if you have overweight or obesity can help slow the progression of CKD and prevent or delay kidney failure. That framing is why kidney health belongs in the conversation before any plan is built: it helps a clinician plan monitoring, choose safe options, and set realistic goals.
Everyday steps that support kidney health
NIDDK's prevention guidance starts from a simple idea: you can protect your kidneys by preventing or managing the health conditions that cause kidney damage, such as diabetes and high blood pressure. On food, it recommends choosing foods that are healthy for your heart and your whole body, including fresh fruits, fresh or frozen vegetables, whole grains, and low-fat or fat-free dairy products, while cutting back on salt and added sugars. It suggests aiming for less than 2,300 milligrams of sodium each day and trying to keep added sugars below 10 percent of your daily calories.
The same guidance covers the rest of the routine: be active for 30 minutes or more on most days, aim for a healthy weight by working with a health care provider or dietitian, aim for 7 to 8 hours of sleep each night, stop smoking, and limit alcohol, which can raise blood pressure and add extra calories. Our food-label, movement, and sleep guides expand on those skills.
One everyday caution matters for kidneys specifically. NIDDK advises being careful about the daily use of over-the-counter pain medications, because regular use of nonsteroidal anti-inflammatory drugs, or NSAIDs, such as ibuprofen and naproxen, can damage your kidneys. That is one reason the full list of everything you take, including over-the-counter products, belongs in your health history, which our supplements and OTC guide covers in detail.
Kidney history, medicines, and questions to bring
If you have ever been told you have kidney disease, if a past blood or urine test flagged kidney function, or if you take medicine that affects the kidneys, that belongs in your health history before starting any weight-care plan or medicine. Two rules follow: never stop or change a medicine on your own, and make sure any new prescriber knows your full kidney history and medicine list.
NIDDK notes that certain blood pressure medicines, called ACE inhibitors and ARBs, may protect the kidneys, and that the names of these medicines end in -pril or -sartan. That is general information, not a recommendation; the decision about any medicine belongs to your clinician.
Useful questions include: When were my kidneys last checked, and what did it show? Do I need a kidney test before or during my weight-care plan? What do my numbers mean for me? Do any of my current medicines affect my kidneys? Which everyday steps matter most in my situation? Write the answers down and keep them with your records, alongside the other health signals covered in our guide to tracking progress beyond the scale.