“Thick ankles” is a common description for a physical feature that can be caused by fluid accumulation, known as edema, or by the structural components of the leg itself. Edema occurs when excess fluid from the blood leaks into the surrounding tissue, often becoming most apparent in the lower extremities due to gravity. While temporary swelling is a frequent, harmless occurrence, persistent or severe ankle thickness may signal an underlying health issue requiring medical evaluation. Understanding whether the thickness is due to fluid retention or a structural variation is the first step in addressing the concern.
Temporary and Lifestyle Causes of Swelling
The most frequent cause of temporary ankle thickness is dependent edema, which is directly related to gravity and how the body manages fluid circulation. Remaining in a single position for an extended period, such as sitting during a long flight or standing all day, causes blood to pool in the lower limbs because the inactive muscles are unable to pump fluids back toward the heart effectively. This pooling increases the pressure within the small blood vessels, leading to fluid leakage into the surrounding tissues.
Dietary choices, particularly a high intake of sodium, contribute significantly to fluid retention and subsequent swelling. Excess sodium prompts the body to hold onto more water to maintain a balanced concentration, which can manifest as noticeable puffiness around the ankles. Additionally, certain medications can cause fluid retention as a side effect, including some blood pressure drugs, such as calcium channel blockers, as well as nonsteroidal anti-inflammatory drugs (NSAIDs) and some hormone therapies.
Environmental factors also play a role, as heat and humidity can cause blood vessels to expand, which makes it easier for fluid to leak into the tissues. Swelling related to these temporary causes is often bilateral, affecting both ankles, and typically resolves with simple measures like elevating the legs above the heart, regular movement, or reducing salt intake.
Systemic Medical Conditions
Swelling in both ankles can also be an outward sign of chronic disease affecting the body’s major organ systems, which are responsible for fluid and pressure regulation. Heart failure is a significant cause, where the heart’s reduced pumping efficiency leads to blood backing up in the veins. This increased pressure in the lower extremities forces fluid out of the capillaries and into the surrounding tissue, causing edema that is often most noticeable in the evenings.
Another circulatory issue, chronic venous insufficiency (CVI), occurs when the valves in the leg veins are damaged and cannot efficiently return blood to the heart. This dysfunction results in blood pooling and persistently elevated pressure in the lower legs, which drives fluid into the ankle tissues. CVI often presents with bilateral swelling that worsens throughout the day and may be accompanied by skin changes over time.
Conditions affecting the kidneys can also lead to bilateral swelling, as these organs are central to filtering waste and regulating fluid volume. Kidney disease, or conditions like nephrotic syndrome, can impair the kidneys’ ability to manage sodium and water balance, causing an excess of fluid to accumulate in the body.
Liver disease, specifically cirrhosis, can also cause edema by reducing the liver’s production of albumin, a protein that helps keep fluid within the blood vessels. A lack of albumin lowers the osmotic pressure in the blood, allowing fluid to leak out into the interstitial spaces.
Structural and Non-Edema Reasons
Not all instances of thick ankles are due to fluid retention; some are purely structural, related to fat deposition or bone shape. Genetics largely determine the dimensions and shape of the ankle bones and the distribution of fat tissue around the lower legs. For some individuals, the appearance of a thick ankle is simply their natural, inherited skeletal and soft tissue structure.
A distinct condition known as Lipedema involves an abnormal, symmetrical accumulation of fat primarily in the legs and ankles, disproportionately sparing the feet. Unlike typical weight gain, this fat is often resistant to diet and exercise and is characterized by a nodular, tender texture. Lipedema is not true edema, though it can complicate into a form of lymphedema later in its progression.
Lipedema is thought to be genetically influenced and often triggered by hormonal changes, such as those occurring during puberty or pregnancy. The fat deposits can cause pain and easy bruising, differentiating it from simple structural thickness or typical obesity.
Warning Signs Requiring Medical Attention
While many causes of ankle swelling are benign, specific symptoms should prompt an immediate medical evaluation. Sudden, unexplained swelling, especially if it only affects one ankle, is a significant warning sign. Unilateral swelling accompanied by pain, redness, or warmth could indicate a deep vein thrombosis (DVT), a blood clot that poses a risk of pulmonary embolism.
Swelling accompanied by systemic symptoms, such as shortness of breath, chest pain, or unexplained weight gain, may signal a serious underlying cardiovascular or renal issue. A fever alongside ankle swelling may point to an infection within the ankle or leg tissue, particularly concerning for individuals with diabetes or other conditions that compromise circulation.
Finally, any swelling that persists for more than a few days despite home care measures like elevation and reduced salt intake warrants a consultation with a healthcare provider. Swelling that leaves a lasting indentation when pressed, known as pitting edema, is a common sign of fluid overload and should be professionally assessed to determine the underlying cause and rule out serious conditions.