5. Sodium and Water Retention
The kidneys play a crucial role in maintaining the right balance of salt and water in the body. If they retain too much, excess fluid builds up in the tissues, leading to edema.
Kidney failure is a common cause, where the kidneys cannot remove excess salt and water effectively. In heart failure, the reduced blood flow to the kidneys tricks them into thinking the body is dehydrated, causing them to hold onto more salt and water, which worsens swelling.
Certain hormonal disorders, like Cushing’s syndrome or hyperaldosteronism, also increase sodium retention and lead to fluid buildup.
In addition, some medications, such as steroids, NSAIDs (painkillers), and calcium channel blockers (used for blood pressure), can trigger edema by causing fluid retention. This is why patients on such medications sometimes notice ankle or leg swelling after prolonged use.