Edema

Edema is the excessive accumulation of fluid in the tissues, which leads to swelling, a feeling of heaviness, and an increase in the volume of certain areas of the body. It is not an independent disease but a signal that the water-electrolyte balance is disrupted, particularly related to sodium regulation.

One of the most common yet little-known mechanisms of edema is a deficiency of salt in the diet, which causes the body to retain water.

Why fluid retention occurs

The main regulator of water balance is sodium. When there is insufficient salt intake, the kidneys activate conservation mechanisms: the renin-angiotensin-aldosterone system (RAAS). This system retains sodium that should have been excreted, along with water.

For every gram of retained sodium, the body holds onto up to a liter of fluid. Therefore, edema often appears in people who have sharply reduced their salt intake or are following salt-free diets.

Along with sodium deficiency, other factors can also provoke fluid retention:

• kidney dysfunction, where the filtration of sodium and water occurs improperly;
• decreased albumin levels in liver diseases, which alters fluid distribution;
• heart failure, where blood flow is impaired and venous pressure increases;
• hormonal changes affecting tissue sensitivity to aldosterone;
• inflammation or injuries accompanied by localized swelling.

How edema manifests

Edema can be localized or generalized. Most often, patients notice:

• swelling of the feet, ankles, and calves;
• swelling of the hands and fingers, making it difficult to remove rings;
• facial swelling, especially in the morning;
• marks from sock elastic that persist for a long time;
• a feeling of heaviness, stretching, or discomfort in the swollen areas.

Diagnosis of the causes of edema

For the correct approach, it is important to determine the source of the water-electrolyte balance disruption. A doctor may prescribe:

• blood and urine tests to assess kidney function and electrolyte levels;
• ultrasound examination of the kidneys, liver, and heart;
• assessment of salt and fluid intake;
• hormonal profile analysis, including aldosterone and cortisol.

Correction and treatment

Treatment of edema always aims to eliminate the underlying cause. If edema is related to salt deficiency, the first step is to restore its adequate level.

• normalization of salt intake according to physiological needs (usually 5–8 g and higher if there are no kidney or heart diseases);
• correction of potassium and magnesium deficiencies, which are involved in water-salt balance;
• moderate physical activity to improve lymph flow;
• adequate hydration considering sodium levels;
• treatment of kidney, heart, and liver diseases if present;
• limiting alcohol and ultra-processed products that disrupt electrolyte balance.

Prevention of fluid retention

To reduce the risk of edema, it is important to maintain a stable water-electrolyte balance:

• avoid salt-free diets and maintain regular sodium intake;
• monitor potassium and magnesium levels in the diet;
• stay active throughout the day and avoid prolonged sitting in one position;
• maintain a healthy weight and level of physical activity;
• ensure regular sleep and reduce stress levels.

Edema is not just a consequence of “excess water,” but an indicator that the body is trying to retain sodium and maintain internal balance. Understanding the real mechanisms of edema allows for a more accurate approach to treatment and helps avoid mistakes in diet and lifestyle.