- 01A normal blood panel is a finding, and it points somewhere
Veins, lymphedema, lipedema and medicines cause most lasting ankle swelling, and none of them shows on a blood test. A clean panel in someone with swollen legs moves the search to a leg exam, a medicine review and a duplex ultrasound of the veins.
Most swollen ankles come from fluid pooling under gravity, and three things narrow down the rest: where the swelling sits (one leg or both), how fast it came (hours or months) and what comes with it (breathlessness, foamy urine, a swollen belly, tiredness). Edema is extra fluid that has leaked out of the blood vessels and settled in the tissue, and gravity pulls it to the lowest point, which is your ankles and feet. The pattern points to the cause long before a blood test does, and when the blood tests all come back normal, that points somewhere too.
When to get help now
Most swollen ankles can wait for a routine visit. These cannot.
- Swelling with breathlessness, chest pain or coughing pink, frothy sputum: call 911 (999 in the UK).
- Only one leg is swollen and it is painful, red, warm or tender in the calf: get same-day medical assessment, because a deep vein thrombosis (DVT, a clot in a deep leg vein) or cellulitis (a skin infection) needs ruling out.
- Pregnant (especially after 20 weeks) with sudden swelling of the face or hands, a bad headache, vision changes or pain under the ribs: call your OB or midwife, or 911, now, as these are warning signs of preeclampsia.
- A swollen belly with confusion, vomiting blood or black stools: call 911.
- Swelling with very little urine, confusion or breathlessness: get same-day care.
- Known heart, kidney or liver disease and the swelling is worse, or your weight has gone up by more than 2 kg (about 4.5 lb) in 3 days: call your care team today 3.
- Swelling that is still there in the morning, keeps rising up the leg, or lasts more than 2 weeks: book a doctor visit.
- Swelling with foamy urine or puffy eyes in the morning: ask for kidney tests.
- Swelling with a swollen belly, yellow eyes or skin, or easy bruising: ask for liver tests.
- Swelling with breathlessness on stairs or lying flat, needing more pillows, or waking short of breath: ask about NT-proBNP.
- Swelling in one leg that has built up slowly, especially after cancer surgery or radiotherapy: see your doctor for a leg exam.
LifeFrom can't examine you or assess a symptom. If something feels seriously wrong, trust that and get care rather than waiting on a test.
A home blood panel is the wrong first step for a possible clot. In NICE guideline NG158, a clinician first scores how likely a DVT is using the two-level Wells score. When the score says DVT is unlikely, a D-dimer blood test is used to rule a clot out; when it says likely, the leg is scanned with ultrasound first, and D-dimer only comes in if that scan is negative 5. A self-ordered D-dimer has no score attached, so a normal result cannot clear a swollen, painful leg. The <a href="/biomarkers/d-dimer">D-dimer page</a> covers what the number can and cannot tell you, and <a href="/learn/clotting-tests-explained">clotting tests explained</a> covers how these tests work.
Sorting the causes by one leg or both
| Pattern | Most likely causes | Who checks it, and how |
|---|---|---|
| One leg, sudden (hours to days) | DVT, cellulitis, sprain or fracture, gout, a burst Baker's cyst behind the knee | Same-day exam; Wells score, ultrasound; X-ray for injury |
| One leg, slow (weeks to months) | Lymphedema after cancer surgery or radiotherapy, venous insufficiency in one leg, a mass pressing on a vein | Doctor's exam, duplex ultrasound |
| Both legs, sudden | New medicine, heat, long flight; less often heart failure, kidney disease flaring, preeclampsia | Medicine review; blood and urine tests; blood pressure in pregnancy |
| Both legs, slow | Venous insufficiency, medicines, heart, kidney, liver, thyroid, lipedema, sleep apnea, idiopathic edema in women | Blood and urine tests below; echo or duplex ultrasound if needed |
Common causes of swollen ankles
Most common first. Everyday causes lead the list; the medical ones are found by the pattern and the tests below.
- 01Gravity, heat, salt and long sits
Standing or sitting still for hours, long flights, hot weather, a salty meal and extra weight push fluid into the lower legs. Both sides swell about equally, worse by evening and mostly gone by morning.
- 02Medicines
Amlodipine and other calcium channel blockers cause ankle swelling in roughly 1 in 10 people in trials, rising with dose 6. NSAIDs, gabapentin, pregabalin, pioglitazone, steroids and hormones can do it too.
- 03Pregnancy and hormones
Most pregnant women get some ankle swelling, especially in the third trimester. Many women also notice puffier ankles before a period or on the pill or HRT.
- 04Chronic venous insufficiency
Leaky valves in the leg veins let blood pool, so the legs feel heavy and ache by evening. It is the most common cause of leg edema in older adults and does not show on a blood test 1.
- 05Heart failure
A weaker pump backs pressure into the veins, so both legs swell along with breathlessness on stairs or lying flat and weight that climbs over days.
- N-Terminal Pro-BNP
- Under 125 ng/L makes heart failure unlikely; a high result leads to an echocardiogram 23
- 06Kidney disease
Kidneys that filter less hold on to salt and water. A heavy protein leak (nephrotic syndrome) adds puffy eyes in the morning and frothy urine.
Can be linked with Chronic kidney disease
- Estimated Glomerular Filtration Rate
- How well the kidneys filter; under 60 for 3 months is CKD 4
- Urine Albumin/Creatinine Ratio
- Whether protein is leaking out through the kidneys
- Creatinine, Serum
- The blood result behind the eGFR
- 07Low albumin and liver disease
Albumin keeps water inside the blood vessels, and a scarred liver makes too little. The belly often swells first, with yellow eyes or skin, and the ankles follow.
- Albumin, Serum
- Swelling becomes more likely as it falls toward 30 g/L (3.0 g/dL)
- Alanine Aminotransferase (ALT)
- Rises when liver cells are damaged
- Aspartate Aminotransferase (AST)
- Read with ALT for liver damage
- 08A clot (DVT) or skin infection
One leg that is swollen, painful, red or warm needs same-day assessment. A clinician scores the risk first, then uses ultrasound or a D-dimer test 5.
- D-Dimer
- Rules a clot out only alongside a clinician's Wells score; a self-ordered normal result cannot clear a painful leg
- 09Underactive thyroid
Hypothyroidism gives firm, puffy swelling of the face, hands and lower legs that does not dent when pressed, often with tiredness and feeling cold.
Can be linked with Hypothyroidism
- Thyroid Stimulating Hormone
- The first thyroid test; high points to an underactive thyroid
- Free Thyroxine
- Checked if TSH is off; low confirms it
- 10Lymphedema and lipedema
Lymphedema follows blocked lymph drainage, often after cancer surgery or radiotherapy, and usually starts on one side. Lipedema is a symmetrical build-up of fat in women's legs that stops at the ankle 7.
Sleep apnea, severe anemia and severe protein malnutrition can also add to swelling in both legs 8.
The everyday reasons, and how to tell it is one
Most swelling in both ankles comes from fluid pooling under gravity. Standing or sitting still for hours, long flights and car rides, hot weather (blood vessels widen to shed heat), a salty meal and carrying extra weight all push more fluid into the lower legs. Hormones move fluid too: many women notice puffier ankles in the days before a period, and estrogen in the pill or <a href="/compounds/hrt">HRT</a> can do the same. Some women, usually before menopause, get swelling with no other cause found; doctors call this idiopathic edema.
Pregnancy is a common everyday cause. Most pregnant women get some ankle swelling, especially in the third trimester and at the end of the day. That swelling is expected; the red flags in the box above are the exception.
Everyday swelling has a recognizable shape: both sides roughly equal, worse in the evening, mostly gone after a night lying flat, no pain, and no other symptoms. Swelling that is still there in the morning, keeps getting higher up the leg, or arrives with any of the symptoms in the sorter deserves a look.
Could it be my tablets?
Medicines often cause swelling in both ankles, and the link is easy to miss. Amlodipine and similar blood pressure tablets called calcium channel blockers (CCBs), widely used for <a href="/conditions/high-blood-pressure">high blood pressure</a>, are the classic example. In a meta-analysis of randomized trials, ankle edema affected roughly 1 in 10 people taking a CCB, and the rate rose with dose 6. The swelling comes from the small arteries in the legs widening while the veins do not, so pressure in the capillaries rises. The body is not holding extra fluid, so water pills (diuretics) are not the usual fix. In trials, adding an ACE inhibitor or an angiotensin receptor blocker (ARB), two other blood pressure drug groups, cut the rate, because those drugs widen the veins as well 9.
| Medicine group | Examples | Why it swells, and what helps (decided with the prescriber) |
|---|---|---|
| Calcium channel blockers | Amlodipine, nifedipine, felodipine | Small arteries widen, veins do not; lower dose, a different blood pressure medicine, or adding an ACE inhibitor or ARB |
| Anti-inflammatory painkillers (NSAIDs) | Ibuprofen, naproxen, diclofenac | Kidneys hold salt and water; review regular use |
| Nerve pain medicines | Gabapentin, pregabalin | Dose-related; review dose or an alternative |
| Diabetes medicine | Pioglitazone | Kidneys hold fluid; not advised in heart failure |
| Steroids | Prednisone, prednisolone | Body holds salt; review dose and duration |
| Hormones | Estrogen in the pill or HRT, testosterone | Body holds salt and water; review type or route |
| Others | Minoxidil, some antidepressants, liquorice in sweets or teas | Liquorice makes the body's own cortisol act like the salt-holding hormone aldosterone; stop it and the swelling settles |
Veins, lymph and fat, which a blood test will not show
Chronic venous insufficiency is the most common cause of leg edema in older adults 1. Valves in the leg veins stop closing properly, blood pools, and the legs feel heavy and ache by evening, with varicose veins and, over years, brown staining or hardened skin around the ankles.
Lymphedema is swelling from blocked lymph drainage, most often after cancer surgery or radiotherapy that removed or damaged lymph nodes. It usually starts on one side, includes the foot and toes, and in time stops leaving a dent when pressed. Lipedema is different again: a symmetrical build-up of fat in the legs, almost only in women, that typically stops at the ankle and spares the feet, and is often mistaken for edema or weight gain 7.
All three show nothing on a blood test. They are found by examining the legs and, where needed, a duplex ultrasound of the veins. A completely normal blood panel in someone with heavy, swollen legs moves the search toward veins, lymph, fat or a medicine; it does not mean the swelling is imaginary.
Swollen ankles and your heart
When the heart pumps less well, pressure backs up into the veins and fluid collects in both legs. Heart failure swelling tends to come with breathlessness on stairs or when lying flat, waking at night short of breath, needing more pillows, tiredness, and weight that climbs over days. The blood test that sorts it is <a href="/biomarkers/nt-probnp">NT-proBNP</a> (N-terminal pro-B-type natriuretic peptide), a fragment released when heart muscle is stretched.
Because very high levels of NT-proBNP carry a poor prognosis, refer people with suspected heart failure and an NT-proBNP level above 2,000 ng/litre (236 pmol/litre) urgently, to have specialist assessment and transthoracic echocardiography within 2 weeks.NICE guideline NG106, Chronic heart failure in adults (2018) 2
Where an example NT-proBNP sits against heart failure cutoffsng/L (same as pg/mL)
NT-proBNP has to be read against the person. It runs higher with age, with reduced kidney function and with atrial fibrillation, and lower in people with obesity, so a value just under a cutoff in a heavier person counts for more 23. A raised result leads to an echocardiogram (heart ultrasound), which shows how the heart is pumping. The difference from the older BNP test is on <a href="/compare/bnp-vs-nt-probnp">BNP vs NT-proBNP</a>, and the other heart blood tests are covered in <a href="/learn/cardiac-markers-explained">cardiac markers explained</a>.
Two less obvious causes sit beside the heart. Obstructive sleep apnea (breathing that stops and starts in sleep, with loud snoring and daytime sleepiness) can raise pressure in the lung arteries, and this pulmonary hypertension strains the right side of the heart and causes swelling in both legs. It is a common cause of leg swelling that has no other explanation 8.
Heart markers to read beside swollen ankles
Swollen ankles and your kidneys
Kidneys that filter less hold on to salt and water, and that extra fluid settles in the ankles. <a href="/conditions/chronic-kidney-disease">Chronic kidney disease (CKD)</a> is defined by the international kidney guideline group KDIGO as an eGFR under 60 mL/min/1.73 m² or a urine albumin-to-creatinine ratio (ACR) of 3 mg/mmol (30 mg/g) or more, lasting longer than 3 months 4. eGFR (estimated glomerular filtration rate) is worked out from blood creatinine, age and sex; ACR measures how much albumin protein is leaking into the urine.
A heavy protein leak causes nephrotic syndrome: more than 3.5 g of protein in the urine a day, blood albumin below 30 g/L (3.0 g/dL), swelling that often starts around the eyes in the morning and spreads to the legs, high cholesterol and frothy urine. <a href="/symptoms/foamy-urine">Foamy urine</a> has its own page, and the wider picture of kidney numbers is on <a href="/learn/kidney-function-explained">kidney function explained</a>. Kidney swelling that comes with very little urine, confusion or breathlessness needs same-day care.
Kidney and protein markers for swollen ankles
CalculatoreGFR calculatorHave a creatinine result? Turn it into an eGFR and see which CKD stage it falls in.Work it out Low albumin and the liver
Albumin is the main protein in blood, and it works like a sponge that keeps water inside the blood vessels. When albumin drops, fluid drifts out into the tissue. Albumin falls during any significant illness or inflammation, and it also runs low when a scarred liver makes too little (cirrhosis), when the kidneys or gut leak it, or when the diet has too little protein. Normal serum albumin is roughly 35 to 50 g/L (3.5 to 5.0 g/dL), and swelling becomes more likely as it falls toward 30 g/L (3.0 g/dL) or below.
In liver disease the belly often swells first (ascites), with yellow eyes or skin, <a href="/symptoms/easy-bruising">easy bruising</a> and tiredness, and the ankles follow. Albumin is read with the liver enzymes ALT, AST and ALP (which rise when liver cells are damaged or bile flow is blocked), bilirubin and total protein; <a href="/learn/liver-enzymes-explained">liver enzymes explained</a> walks through that panel, and <a href="/biomarkers/albumin-serum/low">low albumin</a> covers every cause of a low result. A swollen belly with confusion, vomiting blood or black stools needs 911.
Thyroid, anemia and other less obvious causes
An underactive thyroid causes a different kind of swelling. In hypothyroidism, a gel-like substance builds up in the skin and holds water, giving firm, puffy swelling of the face, hands and lower legs that does not dent when pressed, called myxedema. The first test is <a href="/biomarkers/tsh">TSH</a>, then <a href="/compare/tsh-vs-free-t4">free T4</a> if TSH is off; <a href="/conditions/hypothyroidism">hypothyroidism</a> covers the rest, and a puffy face is covered on <a href="/symptoms/puffy-face">puffy face</a>.
<a href="/conditions/anemia">Severe anemia</a> makes the heart work harder and can add to swelling, which is why a <a href="/learn/cbc-explained">complete blood count (CBC)</a> belongs in the first set of tests. Severe protein malnutrition and restarting food after a long period of eating very little (refeeding) can also cause swollen legs.
Does it leave a dent? The press test
Press a thumb firmly over the shin bone or the top of the foot for 5 to 10 seconds, then let go. If a dent stays, the swelling is pitting edema: free fluid. Clinicians grade it roughly by depth and how long the dent lasts; the table shows one common scale, and the exact depths and times vary between sources.
| Grade | Dent depth (approximate) | How long it lasts (approximate) |
|---|---|---|
| 1+ | About 2 mm | Disappears almost at once |
| 2+ | About 4 mm | 10 to 15 seconds |
| 3+ | About 6 mm | Up to a minute |
| 4+ | About 8 mm | 2 to 5 minutes |
A dent shows fluid, and the heart, kidneys, liver, veins, medicines and gravity all make fluid, so the dent cannot tell you which organ is involved; the pattern and the tests do that. Non-pitting swelling narrows things to lymphedema, thyroid myxedema or lipedema. A fair amount of fluid has to build up before it shows as a dent, so for anyone with heart or kidney disease a daily morning weight is a better early warning than looking at the ankles: heart failure guidance advises acting on a rise of more than 2 kg in 3 days 3.
Which tests, and how to read them together
For swelling in both legs that keeps coming back, the usual first set is a CBC, a kidney panel (creatinine, eGFR, urea, called BUN or blood urea nitrogen in US reports, sodium, potassium), urine ACR or a dipstick for protein, albumin with liver tests, NT-proBNP, and TSH. The <a href="/learn/metabolic-panel-explained">metabolic panel guide</a> covers the kidney and liver lines in one place. Each result means more when read against the others.
| Result pattern | What it points to | Usual next step |
|---|---|---|
| High urine ACR with low albumin | Kidneys leaking protein (nephrotic range if albumin under 30 g/L, 3.0 g/dL) | Repeat ACR, kidney specialist |
| Low eGFR, normal or mildly raised ACR | Kidneys holding salt and water | Repeat in 3 months to confirm CKD, medicine review |
| Low albumin with abnormal liver tests, normal ACR | Liver making too little albumin | Liver ultrasound, liver tests repeated |
| High NT-proBNP with normal kidney tests | Heart under strain | Echocardiogram |
| High TSH, low free T4 | Underactive thyroid | Thyroid follow-up |
| Everything normal | Veins, lymph, lipedema, a medicine or everyday fluid shifts | Leg exam, medicine review, duplex ultrasound if veins suspected |
A raised creatinine behind a low eGFR is explained on <a href="/biomarkers/creatinine-serum/high">high creatinine</a>.
Free, no accountRead your blood testHave a kidney panel, liver tests or NT-proBNP from your doctor? Read every line against the others. A urine ACR or dipstick reads the same way on the <a href="/read/urine-test">urine reader</a>.Read my results
What helps
The cause decides the fix, so these steps are for everyday and vein-related swelling once the red flags are out of the picture. Raise the legs above the level of the heart for a while, a few times a day, so gravity works the other way. Walking and calf raises pump fluid back up the leg, so get up every hour on long sits and flights.
Cutting salt reduces how much water the body holds: US guidance is under 2,300 mg of sodium a day, and UK guidance is under 6 g of salt. Losing weight eases pressure on the leg veins.
Diuretics (water pills) are for real fluid overload from the heart, kidneys or liver. They do little for amlodipine swelling or vein swelling, and they need regular kidney and potassium checks, so they are a prescriber's decision. No supplement has good evidence for reducing leg edema, and liquorice can cause it. Drinking plenty of water does not cause swelling in healthy kidneys, and cutting water to shrink the ankles does not work.
Citations
- Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: diagnosis and management. Am Fam Physician 2013;88(2):102-110
- NICE guideline NG106. Chronic heart failure in adults: diagnosis and management (2018)
- McDonagh TA et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 2021;42(36):3599-3726
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int 2024;105(4S):S117-S314
- NICE guideline NG158. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (2020)
- Makani H, Bangalore S, Romero J, et al. Peripheral edema associated with calcium channel blockers: incidence and withdrawal rate, a meta-analysis of randomized trials. J Hypertens 2011;29(7):1270-1280
- Herbst KL, Kahn LA, Iker E, et al. Standard of care for lipedema in the United States. Phlebology 2021;36(10):779-796
- Ely JW, Osheroff JA, Chambliss ML, Ebell MH. Approach to leg edema of unclear etiology. J Am Board Fam Med 2006;19(2):148-160
- Makani H, Bangalore S, Romero J, et al. Effect of renin-angiotensin system blockade on calcium channel blocker-associated peripheral edema. Am J Med 2011;124(2):128-135
- Norvasc (amlodipine besylate) US prescribing information, Pfizer: adverse reactions, edema by dose
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
