Swollen legs, ankles or puffy eyes can be a sign of a kidney problem, because kidneys that are not working well may hold on to extra fluid and salt or leak protein into the urine. Many other things cause swelling too, from long hours on your feet to heart disease or a new medicine. Clues such as foamy urine, high blood pressure or abnormal kidney tests point more toward the kidneys, and simple urine and blood tests can help sort it out.
Key Takeaways
- Edema is swelling from fluid trapped in the body’s tissues, and it shows up most often in the legs, ankles and feet.
- Damaged kidneys may not remove extra fluid and salt, and kidneys that leak protein can cause puffiness around the eyes.
- Many causes of swelling have nothing to do with the kidneys, including heart failure, liver disease, vein problems, pregnancy and some medicines.
- Foamy urine, high blood pressure and abnormal kidney test results are clues that point toward the kidneys.
- Swelling in one leg with pain, warmth or redness, or swelling with shortness of breath or chest pain, needs medical care right away.
What Is Edema?
Edema is the medical term for swelling caused by fluid trapped in your body’s tissues. It often shows up in the feet, ankles and lower legs, and less often in the hands or face. Painless swelling of the feet and ankles is a common problem, especially in older adults.
Swelling can be small and short-lived, like a sprained ankle, or it can affect larger areas or several parts of the body at once. Cleveland Clinic notes that this second, more widespread type is more serious and can be a sign of heart, liver or kidney failure, or of a circulation problem such as a blood clot. The pattern of your swelling, and what comes with it, helps your doctor work out the cause.
Why Can Kidney Problems Cause Swelling?
Healthy kidneys remove extra fluid and salt from your body. When they are damaged, that fluid and salt can build up, and swelling in the ankles, feet or lower legs may follow. This becomes more likely as chronic kidney disease (CKD) advances, and worsening swelling is one of the symptoms NIDDK lists for advanced CKD.
Kidneys can also cause swelling by leaking protein. Protein in your blood helps hold fluid inside your blood vessels. When the kidneys’ filters are damaged, protein leaks into the urine, blood protein levels drop, and fluid seeps into the tissues. When the loss is large, doctors call it nephrotic syndrome: too much protein in the urine, low levels of a protein called albumin in the blood, swelling, and high cholesterol. It can cause puffy eyelids in the morning, swelling in the legs after standing, foamy urine and weight gain from fluid. Our article on protein in urine explains why that leak matters.
What Else Can Cause Swollen Legs and Ankles?
Swelling has many causes outside the kidneys, and sometimes more than one is at work. They include:
- Standing or sitting for a long time, including long trips
- Vein problems, such as venous insufficiency or varicose veins
- Heart failure or liver disease
- Pregnancy, being overweight, or older age
- An injury, surgery, a leg infection or a blood clot in the leg
- A diet high in salt
Some medicines can also cause swelling. MedlinePlus lists blood pressure medicines called calcium channel blockers, NSAID pain relievers, steroids, hormones such as estrogen and testosterone, and some antidepressants. Never stop a medicine you think is causing swelling without first talking to your doctor or pharmacist.
What Clues Point Toward the Kidneys?
No single sign proves the kidneys are the cause, but some make it more likely. Watch for urine that looks bubbly or foamy, which can mean protein is leaking into it, and for puffiness around your eyes when you wake up. High blood pressure is another clue, because it can be both a cause and a result of kidney disease. Our post on how blood pressure affects kidney health covers that link.
Test results matter most. A blood test called eGFR estimates how well your kidneys filter, and a result under 60 may mean kidney disease. A urine test called uACR measures albumin in the urine, and a result above 30 mg/g may be a sign of kidney disease. Kidney disease is also more likely if you have diabetes, high blood pressure, heart disease or a family history of kidney failure, so swelling deserves a closer look in these cases.
How Does a Doctor Find the Cause of Swelling?
Your doctor will examine you and ask where the swelling is, when it started, what makes it better or worse, and what medicines you take. Bringing a full list of your medicines and supplements helps. Your blood pressure will likely be checked, and tests may include a urinalysis, blood tests, a chest x-ray, an ultrasound of the legs or an ECG, depending on what the exam suggests.
If a kidney cause is suspected, a urine test such as a dipstick or uACR shows how much protein is leaking, and blood tests check kidney function and albumin levels. Sometimes a kidney biopsy is needed to find the exact cause. If you have had tests and are unsure what the numbers mean, our guide to kidney function test results walks through them.
What Helps Reduce Swelling?
The most important step is treating the cause, whether that is a heart, liver, vein or kidney problem. General measures can help while that happens:
- Eating less salt, which helps your body get rid of extra fluid
- Raising your legs above your heart when you lie down
- Wearing support stockings if your doctor recommends them
- Taking breaks to walk around on long trips
Doctors may also prescribe a diuretic, often called a water pill, to help the body get rid of excess fluid. When protein loss is the problem, NIDDK notes that an ACE inhibitor or an ARB may be used to reduce it. Some people with kidney disease are asked to limit fluids as well, but only do this if your doctor tells you to. Do not take water pills that were not prescribed for you.
When Is Swelling an Emergency?
Call 911 if swelling comes with shortness of breath or chest pain, especially chest pressure or tightness. Also call 911 for sudden swelling of the face, mouth or tongue from an allergic reaction. Get medical care right away, the same day, if you have new or worse swelling in only one leg, especially with pain, warmth or redness, because it could be a blood clot. If you cannot reach your doctor quickly, go to an emergency room. The same applies to swelling with a fever, swelling that is getting worse when you have heart or kidney disease, and more than mild or sudden swelling during pregnancy, which may be a sign of preeclampsia.
Make an appointment if swelling keeps coming back or does not go away, if you often wake up with puffy eyes, if your urine looks foamy, or if swelling started after a new medicine. These are not emergencies, but they are worth checking.
Frequently Asked Questions
Is Swelling in One Leg a Kidney Problem?
New or worse swelling in only one leg should be checked right away, because a blood clot is one possible cause. Swelling linked to kidney disease tends to affect larger areas, such as both feet and ankles or the face.
Why Are My Eyes Puffy in the Morning?
Puffy eyes have many causes. Waking up with puffiness that keeps coming back, especially with foamy urine, can be a sign that the kidneys are leaking protein and is worth a urine test.
Should I Drink Less Water to Reduce Swelling?
Not unless your doctor tells you to. Limiting fluids on your own can lead to dehydration, which can harm the kidneys. Eating less salt is a safer general step.
Can Blood Pressure Medicine Cause Ankle Swelling?
Some can, including calcium channel blockers. Talk to your doctor or pharmacist before stopping or changing any medicine.
Does Swelling Mean My Kidneys Are Failing?
Not necessarily. Swelling can come with advanced kidney disease, but it has many other causes, and only tests can show how well your kidneys are working.
Will a Water Pill Fix Kidney-Related Swelling?
A prescribed diuretic can help remove extra fluid, but it does not treat the kidney problem behind it. Your doctor will also look for and treat the cause.
Talk to ANC About Swelling and Your Kidneys
ANC’s clinicians see patients with all types of acute and chronic kidney disease, including glomerulonephritis and kidney disease related to diabetes and high blood pressure. If tests show protein in your urine or reduced kidney function, ask your primary care doctor about a referral, which you usually need, though it may depend on your insurance plan. Contact ANC or call 651-772-6251 with questions.
Sources
- NIDDK: Nephrotic Syndrome in Adults
- National Kidney Foundation: Signs and Symptoms of Kidney Disease
- MedlinePlus: Foot, Leg, and Ankle Swelling
- Cleveland Clinic: Edema
- MedlinePlus: Deep Vein Thrombosis
Medical Disclaimer
This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your specific care and treatment options.
