What organs cause fluid retention?

September 28, 2025 •

3 min read

According to the National Institutes of Health, edema, or fluid retention, is a common symptom of several underlying health issues. The intricate balance of fluid in the body is maintained by a network of organs, and a malfunction in any of them can explain what organs cause fluid retention.

Quick Summary

The primary organs that cause fluid retention are the kidneys, heart, and liver, each playing a critical role in regulating fluid and waste elimination. Conditions like kidney disease, heart failure, and liver cirrhosis disrupt this balance, leading to fluid accumulation.

Key Points

Kidneys filter fluid: When damaged by conditions like chronic kidney disease or nephrotic syndrome, kidneys retain excess fluid and sodium, causing swelling.
Heart pumps blood: A weakened heart in congestive heart failure leads to blood backing up, increasing capillary pressure and causing fluid to leak into tissues.
Liver processes protein: Liver cirrhosis can cause fluid retention (ascites and edema) by increasing pressure in blood vessels and reducing the production of albumin.
Endocrine system uses hormones: Hormones like aldosterone and ADH regulate fluid and electrolyte balance; imbalances can cause or worsen fluid retention.
Lymphatics drain fluid: The lymphatic system removes excess fluid from tissues. Damage or blockage leads to a buildup of lymphatic fluid, a condition called lymphedema.
Many other causes exist: Factors like venous insufficiency, certain medications, malnutrition, and hormonal fluctuations can also contribute to fluid retention.

The Kidneys: The Body's Filtration System

Your kidneys are two bean-shaped organs responsible for filtering waste products, including excess fluid and sodium, from your blood. They play a pivotal role in maintaining the body's fluid and electrolyte balance. When kidney function is impaired, they lose the ability to effectively perform this filtering, causing fluid to back up into the body's tissues.

Chronic Kidney Disease (CKD)

In chronic kidney disease, gradual damage prevents the kidneys from removing waste and excess water, causing fluid overload. This can manifest as swelling, especially in the feet, ankles, and around the eyes.

Nephrotic Syndrome

This condition involves damage to the kidney's filtering units, which leads to excessive protein loss in the urine. Low levels of albumin in the blood decrease oncotic pressure, allowing fluid to leak into tissues.

The Heart: The Circulatory Pump

Congestive heart failure (CHF) is a major cardiac cause of fluid retention due to a weakened heart's inability to pump blood efficiently. This leads to blood backing up in veins, increased pressure in capillaries, and fluid leakage into tissues. Reduced blood flow to the kidneys also triggers hormonal responses that increase salt and water retention. Fluid can accumulate in the lungs, causing breathing difficulties.

The Liver: The Body's Processing Plant

Liver disease, particularly cirrhosis, can cause fluid retention. Scar tissue in cirrhosis obstructs blood flow, increasing pressure in the portal vein (portal hypertension). This can cause fluid accumulation in the abdomen (ascites). A damaged liver also produces less albumin, reducing the blood's ability to retain fluid and leading to widespread edema.

The Endocrine System: Hormonal Regulation

Hormones from endocrine glands regulate fluid balance. The Renin-Angiotensin-Aldosterone System, involving the kidneys and adrenal glands, causes sodium and water retention in response to low blood pressure. Antidiuretic Hormone (ADH) from the pituitary gland helps kidneys reabsorb water. Dysfunction in these systems can lead to fluid imbalances.

The Lymphatic System: The Body's Drainage Network

The lymphatic system collects excess fluid and waste from tissues. Damage or blockage can cause lymphedema, a buildup of lymphatic fluid, often in a limb. Causes include surgery, infection, or cancer.

Comparison of Organ-Related Causes of Edema


Feature	Heart Failure	Kidney Disease	Liver Disease	Lymphedema
Underlying Problem	Weakened heart pump	Impaired kidney filtration	Reduced liver function/scarring	Blocked lymphatic drainage
Common Location	Legs, ankles, abdomen, lungs	Legs, ankles, face (around eyes)	Abdomen (ascites), legs	A single limb, often an arm or leg
Primary Mechanism	Increased backward pressure, hormonal signals	Inefficient waste/fluid removal, protein loss	Portal hypertension, low protein synthesis	Lymphatic fluid buildup
Other Symptoms	Shortness of breath, fatigue, chest pain	Weight gain, foamy urine, fatigue, high BP	Jaundice, easy bruising, mental confusion	Heaviness or tightness in affected limb
Treatment Focus	Improve heart function, diuretics, sodium restriction	Manage underlying kidney issue, diuretics	Low-sodium diet, diuretics, paracentesis	Compression, physical therapy, surgery

Other Contributing Factors and Conditions

Venous Insufficiency: Damaged leg vein valves cause blood pooling and fluid leakage.
Medications: Certain drugs like calcium channel blockers, NSAIDs, and steroids can cause fluid retention.
Malnutrition: Lack of protein can lead to edema due to low albumin.
Hormonal Changes: Fluctuations before menstruation or during pregnancy can cause temporary retention.

When to Seek Medical Attention

Persistent or severe fluid retention requires medical evaluation. Consult a doctor if you experience sudden or severe swelling (especially in one leg), swelling with shortness of breath or chest pain, swelling that worsens, persistent swelling after cancer treatment, or unexplained weight gain/urination changes.

For more detailed information on edema and related conditions, consult the National Kidney Foundation.

Conclusion

Fluid retention is a symptom indicating an imbalance in the body's fluid regulation. The kidneys, heart, liver, and lymphatic system are critical to this balance. Issues with these organs or other factors can cause fluid buildup. Seek medical advice for chronic or severe swelling to identify and treat the root cause.

Frequently Asked Questions

Yes. Sodium binds to water in the body. If you consume too much salt, your body will retain excess water to maintain fluid balance, potentially leading to swelling. This is a common, often temporary, cause of edema.

Not always. While serious conditions like heart, kidney, or liver disease can cause fluid retention, milder, temporary causes include hormonal changes, a high-salt diet, or prolonged sitting or standing. However, persistent or severe swelling should always be medically evaluated.

Yes, several medications can cause fluid retention as a side effect. Common examples include certain high blood pressure medications (calcium channel blockers), NSAIDs, steroid medications, and some diabetes medications.

Edema is the general term for swelling caused by fluid trapped in body tissues, often in the legs, ankles, or feet. Ascites is specifically the accumulation of fluid within the abdominal cavity and is a common symptom of liver disease.

In heart failure, the heart's pump is weak, causing blood to back up in veins. This increases pressure inside capillaries, forcing fluid into surrounding tissues. This backup, along with hormonal changes, triggers the body to retain more salt and water.

Kidney disease, particularly conditions like nephrotic syndrome, can lead to protein (albumin) loss through urine. Low blood albumin decreases the osmotic pressure, allowing fluid to leak into tissues, especially in less dense areas like the eyelids.

If left untreated, chronic fluid retention can lead to complications such as increasing pain, stiff joints, infection risk, stretched skin, poor circulation, and eventually, skin ulcers. It is important to treat the underlying cause.