What is Capillary Leak Syndrome?

Written by Medicover Team and Medically Reviewed by Dr Khan Mohammed Taha Ali , Hematologists

Capillary Leak Syndrome (CLS) is a rare but serious condition.

It happens when tiny blood vessels (called capillaries) leak fluid into nearby tissues.

This leakage causes sudden swelling, low blood pressure, and, in some cases, organ damage.

When the cause is unknown, it's called Clarkson's disease or Idiopathic CLS.

What are the Capillary Leak Syndrome Symptoms and Warning Signs?

Symptoms of Capillary Leak Syndrome can appear suddenly and may worsen quickly. Early identification is crucial to prevent serious complications such as shock or organ failure.

Some signs are mild, while others may require emergency medical care. Understanding these symptoms can help you respond faster and get proper treatment.

Common Symptoms of Capillary Leak Syndrome

Swelling in the arms, legs, or face
Feeling very tired or weak
Nausea or vomiting
Muscle aches or cramps

Severe Symptoms of Capillary Leak Syndrome

Dizziness or feeling faint
Low blood pressure (hypotension)
Trouble breathing

Important: If you notice sudden swelling, dizziness, or low blood pressure, seek emergency care right away.

What are the Different Types of Capillary Leak Syndrome?

Capillary Leak Syndrome can be classified into different types based on its cause. Some people develop it without any clear reason, while others experience it as a side effect of medications or other diseases.

Understanding the types can help with quicker diagnosis and better management of the condition.

Idiopathic Capillary Leak Syndrome (ICLS)

Also called Clarkson's disease, this form has no known cause and is considered the most common type.

Secondary Capillary Leak Syndrome

This type occurs as a result of another health condition or treatment. Common triggers include:

Infections
Autoimmune diseases
Certain medications or cancer treatments

What are the Common Causes and Risk Factors of Capillary Leak Syndrome?

Understanding what may trigger Capillary Leak Syndrome helps with early detection and prevention. Some people are more at risk due to their medical history or current treatments.

Knowing the causes and risk factors empowers you to act fast if symptoms appear.

Capillary Leak Syndrome Causes

Unknown causes (idiopathic)
Viral infections like the flu, hepatitis, or HIV
Some cancer drugs, like Interleukin-2
Autoimmune diseases
Allergic reactions
Chemotherapy

Capillary Leak Syndrome Risk Factors

People with immune system problems
Those on immunotherapy or chemotherapy
Anyone with frequent infections
Patients with cancer

If you are on cancer treatment or immune therapy, report new symptoms like swelling or lightheadedness to your doctor right away.

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How is Capillary Leak Syndrome Diagnosed?

Diagnosing Capillary Leak Syndrome is challenging because its symptoms can resemble other serious conditions. Doctors use a mix of clinical exams, blood tests, and imaging to reach a diagnosis.

Early diagnosis is key to starting treatment before complications arise.

Diagnostic Approaches Include

Medical History and Physical Exam:

Doctors look at your symptoms, medical history, and overall health. This helps rule out other possible causes.

Blood Tests (Lab Work):

Complete blood count (CBC) to check for thickened blood (hemoconcentration)
Kidney function tests
Electrolyte levels

Imaging Scans:

Ultrasound, CT scan, or MRI to spot fluid buildup in the body

Differential Diagnosis:

Other conditions like sepsis, severe allergies (anaphylaxis), or nephrotic syndrome must be ruled out first.

What Are the Treatment Options for Capillary Leak Syndrome?

Treatment focuses on stabilising the patient during a flare-up and reducing the risk of future episodes. Both emergency interventions and long-term management are needed to control symptoms and protect vital organs.

Acute Phase Treatment

During a CLS attack, fluid leaks from the blood vessels into surrounding tissues. Quick action is essential to prevent shock and organ damage. These treatments are usually given in a hospital or ICU setting:

IV Fluids: To keep blood pressure and hydration stable
Vasopressors: Help tighten blood vessels and support blood flow
Electrolyte Correction: Replaces important minerals lost through fluid shifts

Long-Term Management

After the acute phase, long-term care focuses on preventing recurrences. Doctors monitor symptoms closely and prescribe medications to manage the immune response and reduce inflammation.

Preventive Medications: Drugs like theophylline and terbutaline may reduce flare-ups
Immune Therapy: Helps regulate the body's immune response
Lifestyle Tips: Avoid known triggers like infections or overexertion
Regular Monitoring: Keeps symptoms in check and catches early signs of recurrence

Our ICU and vascular care teams are trained to manage rare conditions like CLS. We provide customised treatment plans and ongoing support at every stage.

When Should You See a Doctor?

Early detection can prevent life-threatening complications. CLS often starts suddenly and may look like other conditions, so paying attention to early symptoms is key.

High-risk individuals must be extra cautious and seek help without delay if symptoms occur.

See a doctor right away if you notice:

Sudden swelling in your legs, arms, or face
A sharp drop in blood pressure
Fainting spells or extreme tiredness

High-risk patients: (e.g., those on immunotherapy, with autoimmune conditions or recent infections) should consult a doctor immediately upon experiencing these symptoms.

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What is the Recovery Process After Capillary Leak Syndrome Treatment?

Recovery from CLS varies depending on the severity and frequency of episodes. Some people bounce back quickly after treatment, while others need ongoing care.

Monitoring, rest, and nutrition all play a role in restoring health and preventing the condition from returning.

Post-Treatment Recovery Includes

Regular checkups and lab tests to monitor progress
Preventive medications may be prescribed
A high-protein, high-fluid diet to help the body heal
Rest and avoid heavy physical activity

Long-Term Outlook

Recovery is possible, but some people may have repeat episodes. Ongoing support can help manage symptoms and improve quality of life. Nutrition guidance, personalised care, and gentle physical rehabilitation may be recommended based on individual needs.

What Precautions Can Help Prevent Capillary Leak Syndrome?

While there is no sure way to prevent CLS, certain lifestyle changes and medical precautions can lower the risk.

Knowing your triggers and staying vigilant after past episodes can help reduce flare-ups and keep the condition under control.

Capillary Leak Syndrome Prevention Tips

Avoid known medication triggers
Manage autoimmune or allergic conditions effectively
Seek early treatment for infections

Capillary Leak Syndrome Complications

If not treated in time, CLS can lead to serious health issues, some of which may be life-threatening. Complications usually arise from severe fluid loss and organ strain.