Swelling of the legs — one leg, or both?

The question that splits the diagnosis

Before anything else: is it one leg or both? The distinction is not a formality, and it does more diagnostic work than most blood tests. Bilateral or generalised swelling points to a systemic cause — heart failure, kidney disease, liver disease, low blood protein, obstructive sleep apnoea, or a drug. Unilateral swelling points to something in that leg — deep vein thrombosis, chronic venous insufficiency, lymphoedema, cellulitis, or a mass obstructing the vein.^[1]

The second question is how quickly it appeared. Swelling of one leg that came on over hours to a couple of days needs assessment for a clot the same day. Swelling that has crept up over months is a different investigation and a different urgency.

The third question — and this is the one most often skipped — is what tablets you are taking.

The tablet that causes it in one in ten people

Amlodipine is probably the most widely prescribed blood pressure tablet in India, and ankle swelling is its commonest side effect. The numbers are precise, because a meta-analysis of 106 studies and 99,469 participants measured them: peripheral oedema in 10.7% (95% CI 10.6–10.9) on calcium channel blockers against 3.2% (3.1–3.3) on control.^[2]

Three features of that finding are what make it clinically useful:

The duration figure is the one that defeats the diagnosis in practice. Someone started on amlodipine in January whose ankles swell in August does not connect the two, because the tablet has been "fine" for months. Nearly one in four long-term users is affected.^[2]

Two practical points follow. First, do not stop a blood pressure tablet on your own — bring the strip to the consultation. Second, stopping it is often not the answer anyway: adding an ACE inhibitor reduces calcium-channel-blocker oedema,^[1] and switching within the class is another option, so a tablet that is controlling your blood pressure well does not have to be abandoned.

Both legs: the systemic causes

The heart

Bilateral swelling that is worse in the evening, better after a night lying down, and comes with breathlessness — particularly breathlessness lying flat or waking you at night — is heart failure until shown otherwise. The Indian context matters: in the National Heart Failure Registry of 10,850 patients, the mean age at presentation was 59.9 years, about a decade younger than in high-income countries, with ischaemic disease in 71.9% and rheumatic heart disease in 5.4%; one-year mortality was 22.1%.^[3] Echocardiography is what settles it and is referred.

The kidneys

Kidney disease produces swelling in two different ways, and they need separating. Chronic kidney disease causes fluid retention as filtration falls. Nephrotic syndrome causes swelling by losing protein into the urine, and it characteristically produces puffiness around the eyes in the morning as well as leg swelling, often with frothy urine.

Chronic kidney disease affects around 17.2% of Indian adults in the SEEK-India study, with eGFR below 60 in 5.9%, and anaemia in 40.7% of those with CKD.^[4] The more sobering figure comes from the Indian CKD Registry of 52,273 patients across more than 200 centres: 48% presented already in Stage V, with diabetic nephropathy the commonest cause at 31%.^[5] Kidney disease is quiet until late, and swelling is often the first thing that brings someone in.

In eastern India, nephrotic syndrome is the commonest reason for a kidney biopsy — 63.6% of 1,312 native kidney biopsies in a Patna series — with focal segmental glomerulosclerosis the leading pattern at 23%.^[6] Urine albumin, creatinine and eGFR are the first tests, and they are inexpensive.

The liver, and low blood protein

Cirrhosis causes leg swelling together with abdominal distension. In West Bengal, alcohol-use disorder affects about 3.04% of adults, with a treatment gap of 89.2% — and notably a female-to-male ratio of 1:5 in West Bengal against 1:18 nationally.^[7] A Kolkata series of 395 patients with alcohol-related liver disease found that 79.7% already had cirrhosis or acute-on-chronic liver failure at presentation.^[8]

Low blood protein from malnutrition or protein loss also causes swelling, and it is worth remembering alongside anaemia in a state where 71.4% of women and 38.9% of men aged 15–49 are anaemic.^[9]

One leg: the local causes

Sudden unilateral swelling with pain and warmth is deep vein thrombosis until excluded, and the exclusion is a duplex ultrasound rather than an examination. It is worth knowing that clinical suspicion is a poor test on its own: up to 75% of legs that look like DVT turn out to be something else — a ruptured Baker's cyst, a calf muscle tear, cellulitis, a popliteal aneurysm, or a soft-tissue mass.^[10] That cuts both ways. It means most suspected clots are not clots; it also means the diagnosis cannot be made or dismissed by looking.

Cellulitis — a spreading, hot, red, tender area with fever — is a clinical diagnosis and needs antibiotics promptly. Chronic venous insufficiency produces gradual swelling with skin changes and varicose veins, worse at the end of the day.

Lymphatic filariasis

This needs stating carefully, because the temptation is to overstate a locally resonant diagnosis. Lymphatic filariasis is endemic in West Bengal — official figures record 12 endemic districts in the state, with 110,629 clinically manifested cases recorded in 2013 and mass drug administration coverage of 86.77% that year.^[11] Nationally, 348 districts across 20 states and union territories are endemic, 143 of them have stopped mass drug administration after clearing transmission assessment surveys, and the elimination target is 2027.^[12]

Whether Cooch Behar itself is currently on the endemic list could not be established from a definitive source. One peer-reviewed paper covering the sub-Himalayan districts names Cooch Behar among the endemic districts; another published list of West Bengal endemic districts omits it. The official programme page publishes its district list only as an image. Rather than assert either version, this page states the uncertainty, and the position at the clinic is that the diagnosis is considered on the clinical picture and a night blood film where the history fits, not on a district list.

Two further facts are relevant. Mass drug administration was suspended in March 2020 and did not resume until February 2024, so transmission was not interrupted through that period.^[13] And filarial lymphoedema is not always accompanied by detectable microfilariae — in a survey across four West Bengal districts, 2.13% had chronic lymphoedema while being microfilaria-negative.^[13] That survey was conducted in high-burden coalfield communities using non-probabilistic sampling and its prevalence figures are an upper bound for those districts, not a figure for Cooch Behar.

What matters clinically: filarial lymphoedema is usually unilateral or asymmetric, does not pit deeply once established, involves the foot and toes, and is progressive. It is a different examination finding from the soft pitting swelling of heart failure or amlodipine, and it is treated differently.

What is done at the consultation

One leg or both. How fast it came on. Whether it pits. Whether the face is puffy in the morning. What the urine looks like. What tablets you are on — bring the strips. Then an ECG, blood count, creatinine and eGFR, urine albumin, liver function and albumin, and thyroid function. Echocardiography and duplex ultrasound are arranged where indicated; there is no ultrasound machine at the clinic. Reports are reviewed with you at follow-up, which is not charged within 10 days.