Why do my ankles swell?

Swelling or oedema of lower limbs is due to liquid accumulating in the interstitial space, i.e. outside the usual ducts transporting these fluids, which are the venous and lymphatic systems. Plasma circulating through our veins or lymphatic liquid abandon their circulation ducts for different reasons and accumulate in the interstitial space (below the skin). When this accumulation occurs in your ankles, we doctors talk about malleolar or pretibial oedema or oedema of the lower limbs in general.

Given the complexity and extension of this topic, we’re only going to deal with the most frequent causes, where patients with swollen ankles come to see a cardiologist.

Firstly, it’s important to differentiate an oedema which occurs only in one leg from that occurring in both. If it’s only one leg, where it’s always a local problem of that particular leg. However, when an oedema affects both legs, it may simply be a local problem affecting both legs or more often than not a general problem.

The 3 most common causes for oedema in one leg are:

• Secondary to trauma in said limb.
• Secondary to infection in said limb.
• Secondary to venous problems such as internal varicose veins or thrombosis. In both situations there is incorrect blood return via said veins; therefore, internal pressure increases and plasma leaves the same.

Other less common causes are: local infections, radiotherapy, surgery, etc.

The most frequent causes of oedema in both ankles are:

• Heart failure – this occurs due to pressure increase throughout the venous circuit, since the right cavities of the heart are failing in their function to accept all the blood reaching them through the veins and sending it to the lungs for their oxygenation. This is usually accompanied by ascites (accumulation of liquid in the abdomen, increase in the size of the liver, with pain on palpation of same, and frequently shortness of breath.
• Problem compressing veins and hindering return circulation, such as obesity, pregnancy, and those while not causing compression hinder blood evacuation from lower limbs, such as standing still for a prolonged period or being and immobile (plane trips).
• Treatment with drugs, usually antihypertensives: All drugs which produce vein dilation may cause oedema in your ankles. Those which most frequently cause this are the so-called calcium channel blockers (amlodipine, nifedipine, nicardipine, nisoldipine, etc.)
• Varicose veins in both legs.

Other less frequent causes are: kidney (nephrotic syndrome), liver (liver failure) and endocrine (Cushing’s syndrome, myxedema,…) problems. There are other even rarer disorders which also cause oedema, and which we’re not going to discuss.

How soon should I contact my doctor if my ankles swell?

• If accompanied by redness, pain and increase in your temperature.
• If accompanied by shortness of breath and/or increase in abdomen size.

To sum up, legs may swell for many reasons, and they should all be examined and treated. We must be clear about the reasons we need to consult a doctor as soon as possible.