Swollen Ankles and Feet: Common Causes, Urgent Signs and the Tests That Check Your Kidneys, Liver, Heart and Thyroid

Swollen ankles and feet are often caused by standing, heat, salt, travel, pregnancy or a medicine. Swelling in one leg, or swelling with shortness of breath or chest pain, needs urgent care. When swelling keeps coming back, blood and urine tests check the kidneys (creatinine, eGFR, urine albumin), the liver and albumin, the heart (NT-proBNP) and the thyroid (TSH).

Published: November 13, 2026
Read time: 14 min read
Medically reviewed by: Rhonda Collins, FNP-C

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Swollen ankles and feet are common, and most often come from everyday things: standing for a long time, long car rides or flights, warm weather, too much salt, pregnancy or a medicine ^[1]^[2]. The swelling is fluid that has built up in the tissues, called edema, and gravity makes it collect in the lower legs ^[1].

Swelling can also be a sign of a problem with the heart, kidneys or liver, and, less often, the thyroid ^[1]^[2]. In those conditions there is too much fluid in the body, and it collects in the legs ^[1]. The sections below cover which swelling needs urgent care, which is everyday, and which blood and urine test checks each organ.

When swollen ankles and feet are an emergency

Call 911 or your local emergency number if swollen feet or legs come with shortness of breath or chest pain, especially chest pain that feels like pressure or tightness ^[1]. Do not wait for a lab test.

Contact a provider right away if ^[1]:

the swelling is new or worse in only one leg;
the swollen foot or leg is red or warm to the touch;
you have a fever;
you are pregnant and have more than mild swelling, or a sudden increase in swelling;
you have heart disease or kidney disease and the swelling gets worse;
you have liver disease and now have swelling in your legs or belly.

Swelling in one leg matters because of blood clots. A deep vein thrombosis (DVT) is a clot in a deep vein, most often in the lower leg or thigh, and it usually affects one side of the body ^[3]. It can cause swelling, pain or tenderness, redness and warmth ^[3]. A DVT should be taken seriously because the clot can travel to the lungs, a pulmonary embolism, which can cause shortness of breath and pain when breathing ^[4]. A blood test you order yourself is not the right next step for any of these signs. They need to be examined in person.

Everyday causes of swollen feet and ankles

Long airplane flights or car rides, and standing for long periods, often lead to some swelling in the feet and ankles ^[1]. Slight swelling of the lower legs is also common in warm summer months, especially after a lot of standing or walking ^[2]. This kind of swelling is usually painless and may affect both legs ^[1].

Other common causes are:

Salt. Too much salt or sodium is a listed cause of swelling ^[2].
Body weight and age. Swelling is more common in people who are older or overweight ^[1].
Hormones. Swelling can happen during parts of the menstrual cycle and in people who take estrogen ^[1].
Pregnancy. Most people have some swelling during pregnancy. More severe swelling during pregnancy may be a sign of preeclampsia, a serious condition that includes high blood pressure, so sudden or more than mild swelling in pregnancy needs a call to your provider right away ^[1].
Medicines. Several classes of medicine can cause leg swelling, including some antidepressants, some blood pressure medicines, hormones, nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids ^[1]. Do not stop a medicine you think is causing swelling without first talking with your provider ^[1].

Everyday swelling with a clear cause, in both ankles, that goes away does not need a blood test. MedlinePlus suggests raising your legs above your heart when lying down, moving your legs, eating less salt, support stockings and breaks to move around when traveling ^[1]. Contact a provider if self-care does not help or the swelling gets worse ^[1].

Vein problems and lymphedema

Veins that cannot move blood back up to the heart well, called venous insufficiency, are a common cause of leg swelling, most often because of varicose veins ^[1]^[5]. Venous insufficiency can also cause aching, heaviness or cramping in the legs, pain that gets worse when standing and better when the legs are raised, itching, and skin changes such as thickening or slow-healing sores near the ankles ^[5].

Lymphedema is a different type of swelling, caused by a buildup of lymph fluid when the lymph system is damaged or blocked ^[6]. It usually affects the arms or legs. Causes include infection, cancer, scar tissue from radiation or lymph node surgery, and inherited conditions ^[6]. Leg swelling can also follow pelvic surgery, especially for cancer ^[1].

Vein problems and lymphedema are checked with an exam and, for veins, an ultrasound, not with a blood panel ^[1]. Blood tests are more useful for the organ causes below.

Swollen ankles and the kidneys

Kidney disease can cause swelling in the legs, feet or ankles, because the kidneys cannot remove extra fluid and salt from the body ^[7]. Less often the swelling shows in the hands or face ^[7]. It is more common when kidney disease is very advanced or when a lot of protein is leaking into the urine ^[7].

Most people with early chronic kidney disease (CKD) have no symptoms, and for many people the only way to find it is with blood and urine tests ^[7]. Other symptoms of advanced CKD include foamy urine, a change in how often you urinate, tiredness, itching, muscle cramps, and worsening swelling ^[7].

When a lot of protein leaks into the urine, the result is called nephrotic syndrome: protein in the urine, low albumin in the blood, swelling, and high cholesterol ^[9]. Its swelling can include puffy eyelids and swelling in the legs, ankles and feet, along with foamy urine and weight gain from fluid ^[9].

Because swelling from the kidneys is more common when protein leaks into the urine, a urine albumin-to-creatinine ratio is one of the two main kidney checks, alongside a blood test for GFR ^[7]^[8]. Albumin is a protein that can pass into the urine when the kidneys are damaged ^[8].

The tests that check the kidneys are:

Creatinine and eGFR. Creatinine is a waste product from muscle, and its level in the blood is used to estimate the glomerular filtration rate (GFR). As kidney disease gets worse, creatinine goes up ^[8]. A GFR of 60 or more is in the normal range, less than 60 may mean kidney disease, and 15 or less is called kidney failure ^[8]. See eGFR.
Urine albumin-to-creatinine ratio (UACR). A healthy kidney does not let albumin into the urine. A UACR of 30 mg/g or less is normal, and more than 30 mg/g may be a sign of kidney disease ^[8]. Temporary rises can come from exercise, fever, some medicines and inflammation, so an abnormal result is usually repeated over the next three to six months ^[10].

For the other signs that point to the kidneys, see kidney disease symptoms and blood tests and the UACR test explained.

Swollen ankles, the liver and low albumin

Liver disease can cause swelling in the lower legs, ankles or feet, and swelling of the belly from fluid, called ascites ^[11]. In cirrhosis, these usually appear later, as liver function gets worse ^[11]. Other late signs include yellow skin or eyes (jaundice), easy bruising, severe itching and darker urine ^[11].

Low albumin is one reason the liver and the kidneys both cause swelling. Albumin is a protein made by the liver that keeps the fluid part of the blood inside the blood vessels. Without enough albumin, fluid can leak out and build up in the lungs, belly or other parts of the body ^[12]. A damaged liver may not make enough albumin, and damaged kidneys may let albumin pass into the urine ^[12]. Too little albumin in the blood is a listed cause of swelling in its own right ^[2].

The tests that check this question are:

Albumin. Lower-than-normal albumin may be a sign of liver disease, kidney disease, malnutrition, infection, digestive diseases that affect protein absorption, or thyroid disease. Albumin alone cannot diagnose a condition and is read with other results ^[12]. A standalone albumin blood test is available. See low albumin symptoms.
Liver tests. A liver panel measures albumin, total protein, bilirubin, and the liver enzymes ALP, ALT and AST, among others. Liver tests alone usually cannot diagnose a specific disease, so abnormal results lead to more tests ^[13]. Many liver function tests are included in a comprehensive metabolic panel (CMP) ^[13].

For more on the liver, see liver disease symptoms and blood tests.

Swollen feet and heart failure: the NT-proBNP test

Heart failure can cause swelling in the ankles, feet, legs, belly and the veins in the neck ^[14]. This swelling is a symptom of right-sided heart failure, which can also cause nausea, loss of appetite, needing to urinate often, and weight gain ^[14].

Shortness of breath is the most common symptom of heart failure ^[15]. One of the first signs may be feeling short of breath after routine activities like climbing stairs, and some people are short of breath when lying flat ^[14]. Swelling together with shortness of breath or chest pain needs emergency care ^[1], not an at-home test.

NT-proBNP and BNP are blood tests used to help confirm or rule out heart failure in people who have symptoms ^[15]. The heart makes more of these proteins when it has to work harder to pump blood ^[15]. In someone with symptoms:

normal levels usually mean heart failure is unlikely, although obesity can make levels read lower than they really are ^[15];
higher-than-normal levels for your age and sex mean you could have heart failure, and other heart tests are usually done to confirm it ^[15];
kidney failure, other heart conditions and some lung conditions can also raise these levels ^[15].

Doctors diagnose heart failure from your history, an exam and test results, including blood tests such as BNP and imaging such as an echocardiogram ^[16]. Mito offers an NT-proBNP blood test for people who are not having urgent symptoms and want to discuss the result with a clinician.

Swelling and the thyroid

Thyroid disease is a listed cause of swelling ^[2]. An underactive thyroid (hypothyroidism) can cause a puffy face, hands and feet as a late symptom if it is not treated, and a provider may find swelling of the arms and legs on exam ^[17]. Its more common symptoms include tiredness, feeling cold, weight gain, dry skin, and joint or muscle pain ^[17].

A TSH blood test is the first check. A higher-than-normal TSH is most often due to an underactive thyroid ^[18]. If TSH is abnormal, a free T4 test usually follows ^[17]^[18]. A TSH blood test can be ordered on its own.

Pitting vs non-pitting edema

Pitting edema leaves a dent in the skin after you press the swollen area with a finger for about 5 seconds, and the dent slowly fills back in. Non-pitting edema does not leave a dent ^[2]. MedlinePlus describes edema both ways but does not tie pitting to one cause, so a dent alone does not tell you which organ is involved ^[2].

Fluid can build up for a while before swelling shows. In generalized fluid retention, a person’s weight may rise by nearly 10% before pitting edema is visible ^[19]. A quick gain in weight over days to weeks can be a sign of swelling ^[2].

Edema can affect one leg or both, one area or the whole body, and where it shows helps a clinician narrow the cause ^[19]. New swelling in only one leg needs to be checked right away, because a blood clot or a leg infection can cause it ^[1]^[3].

Which tests check swollen ankles and feet

MedlinePlus lists blood tests such as a complete blood count (CBC) or blood chemistry, a urinalysis, and imaging such as a Doppler ultrasound of the leg veins among the tests a provider may use for leg, foot and ankle swelling ^[1]. For swelling in general, it adds albumin, electrolytes, kidney function tests and liver function tests ^[2]. Each cause maps to specific tests:

Likely cause	What points to it	Test that checks it
Standing, travel, heat, salt, pregnancy or a medicine	Both ankles, a clear trigger, goes down with rest ^[1]^[2]	None if it settles
Blood clot (DVT) or leg infection	One leg, pain, redness, warmth or fever ^[1]^[3]	Prompt in-person exam and Doppler ultrasound ^[1]
Kidney disease	Foamy urine, puffy eyelids, change in urination ^[7]^[9]	Creatinine and eGFR, urine albumin-to-creatinine ratio ^[8]
Liver disease or low albumin	Belly swelling, yellow skin or eyes, itching, easy bruising ^[11]	Albumin and liver tests (ALT, AST, ALP, bilirubin) ^[12]^[13]
Heart failure	Shortness of breath, trouble lying flat, weight gain ^[14]^[15]	NT-proBNP or BNP, then heart imaging ^[15]^[16]
Underactive thyroid	Tiredness, feeling cold, dry skin, puffy face and hands ^[17]	TSH, then free T4 ^[18]

How to read the results together

Rising creatinine and a falling eGFR, with albumin in the urine, point to the kidneys ^[8].
Low albumin in the blood with a high urine albumin fits protein loss through the kidneys, as in nephrotic syndrome ^[9]^[12].
Low albumin with abnormal liver enzymes or bilirubin points toward the liver ^[12]^[13].
Normal kidney and liver results with a high NT-proBNP in someone with symptoms points toward the heart, though kidney failure can also raise NT-proBNP ^[15].
A high TSH points toward an underactive thyroid ^[18].
All of these normal makes kidney, liver, heart and thyroid causes less likely, which leaves everyday, vein and medicine causes. A clinician can sort these out with an exam ^[1].

Mito tests for swollen ankles and feet

The Comprehensive Metabolic Panel (CMP) covers the kidney and liver questions in one draw: creatinine, eGFR and BUN for the kidneys, and albumin, total protein, ALT, AST, alkaline phosphatase and bilirubin for the liver, plus electrolytes and glucose. The CMP measures 14 substances in a blood sample ^[20].
The Albumin and Creatinine with Albumin-Creatinine Ratio (ACR), Urine Test checks whether albumin is leaking into the urine.
The NT-proBNP test checks the heart question when you are not having urgent symptoms.
The TSH test checks the thyroid.
A complete blood count (CBC) is one of the blood tests MedlinePlus lists for leg swelling ^[1]. It can show anemia and signs of infection ^[21].

Swelling in specific situations

Mito has shorter pages on swelling in particular situations. Each one covers its own context:

References

Frequently asked questions

When should I worry about swollen feet and ankles?

Call 911 or your local emergency number if swelling comes with shortness of breath or chest pain, especially chest pressure or tightness. Contact a provider right away if the swelling is in only one leg and is new or getting worse, if the leg is red or warm, if you have a fever, if you are pregnant and the swelling is more than mild or sudden, or if you have heart, kidney or liver disease and the swelling gets worse. Mild swelling in both ankles after standing, travel or a hot day is common.

Does a swollen foot mean heart failure?

Not usually on its own. Swelling in the ankles, feet and legs is one symptom of heart failure, but so are shortness of breath after routine activity, trouble breathing when lying flat, tiredness and weight gain. Many everyday things cause swollen feet too, such as standing, heat, salt and some medicines. Swelling with shortness of breath or chest pain needs emergency care: call 911. An NT-proBNP or BNP blood test is used to help confirm or rule out heart failure in people who have symptoms.

Can dehydration cause swollen feet?

Dehydration is not one of the causes of foot, leg and ankle swelling that MedlinePlus lists. The causes it lists include standing for long periods, long trips, warm weather, too much salt, pregnancy, some medicines, vein problems, and heart, kidney or liver disease. If your feet swell in the heat, warm weather itself is a listed cause.

How do you reduce swelling in your feet and ankles?

MedlinePlus suggests raising your legs above your heart while lying down, moving your legs, following a low-salt diet, wearing support stockings, taking breaks to move around when traveling, and avoiding tight clothing around the thighs. Do not stop a medicine you think is causing the swelling without talking with your provider first. Swelling that does not improve, or keeps coming back, is worth checking.

Why are my ankles swollen but they do not hurt?

Painless swelling of the feet and ankles is common, especially in older people. It often affects both legs and shows most at the ankles because of gravity. Common reasons include standing or sitting for a long time, travel, heat, salt, some medicines and vein problems. Painless swelling in both legs that keeps coming back can also come from the kidneys, liver, heart or thyroid, which blood and urine tests can check.

Thyroid function tests

Thyroid Antibodies Panel
View current details, availability, and member pricing.
TSH Blood Test with Reflex to Free T4
The most sensitive first-line marker for thyroid function, behind fatigue, weight change, and mood shifts.
Triiodothyronine, Free (Free T3) Blood Test
The active thyroid hormone, most useful for confirming and pinpointing hyperthyroidism.
Free Thyroxine (Free T4) Blood Test
The unbound thyroid hormone actually available to your tissues, and the usual next step after an abnormal TSH.