Capillary leak syndrome its causes symptoms and treatment

In the field of medicine, there are some extremely rare diseases that can be both dangerous and confusing at the same time. One of these is Systemic Capillary Leak Syndrome (SCLS), also known as Clarkson’s disease.This condition occurs suddenly and affects the balance of fluids in the body, where fluid leaks from the small blood vessels into surrounding tissues. This can lead to a severe drop in blood pressure, swelling, and intense symptoms that require urgent medical intervention.What makes this condition particularly important is that it is very rare, and its early symptoms often resemble those of other diseases, which can delay diagnosis in some cases. In this article from Deli Med, we will learn together all the important details about this disease: its causes, symptoms, complications, treatment methods, and whether it can actually be life-threatening or not.

What is Systemic Capillary Leak Syndrome (SCLS)?

Systemic Capillary Leak Syndrome (SCLS), also known as Clarkson’s disease, is a rare and serious disorder in which plasma leaks from the small blood vessels into surrounding tissues. This leads to a sudden drop in blood pressure, severe body swelling, and in some cases, failure of vital organs. The condition usually occurs in recurrent attacks and can become life-threatening if not treated quickly.

⚠️ Is the disease dangerous?

Yes. It can be very dangerous during acute attacks, especially if not treated promptly, as it may lead to severe low blood pressure and shock. However, careful medical follow-up and preventive treatment can significantly reduce the severity and frequency of episodes.

Does the disease occur once or recur?

It typically occurs in recurrent episodes, where the patient is stable and symptom-free between attacks.

Is there a definitive cure?

Currently, there is no definitive cure, but the disease can often be controlled with preventive treatments that reduce the frequency and severity of attacks.

⏱️ How long does an attack last?

An attack usually lasts 1 to 3 days, but in severe cases it may last longer depending on the patient’s condition and response to treatment.

Can an attack be treated at home?

No ❌
An attack requires immediate hospital care, often in an intensive care unit (ICU), due to the risk of sudden severe blood pressure drop and the need for close fluid and circulation monitoring.

❓ Is it hereditary?

In most cases, it is not hereditary and appears without a clear family history.

❓ Who is most at risk?

Mostly affects adults, especially middle-aged individuals
Rare in children
Can affect both men and women, with a slight male predominance in some studies

❓ Can it be detected before an attack?

It is very difficult to detect before attacks because:

Patients are usually completely normal between episodes
Lab tests may appear normal during inactive periods

❓ Does blood pressure increase or decrease?

During an attack:

Blood pressure drops sharply and dangerously
Between attacks:
Blood pressure is usually normal

❓ Is it related to allergies?

No ❌
However, during attacks, symptoms may resemble severe allergic reactions (anaphylaxis), which can lead to initial misdiagnosis.

❓ Can it cause blood clots?

Yes, in some cases the risk of blood clots increases during attacks due to increased blood viscosity caused by fluid leakage. This is managed under strict medical supervision.

❓ Does pregnancy affect the disease?

Yes. Pregnancy can place additional stress on the body, so:

Close medical monitoring is required
Management is individualized before and during pregnancy
Decisions depend on disease severity and stability

❓ Is exercise allowed?

Not completely forbidden, but:

Light exercise is recommended
Avoid intense or sudden physical exertion
Stop immediately if unusual symptoms occur

❓ Can stress trigger an attack?

Yes. Severe emotional stress or physical exhaustion may trigger attacks in some patients.

❓ Are there foods to avoid?

No specific diet restrictions, but it is recommended to:

Stay well hydrated
Avoid dehydration
Maintain a healthy, balanced diet

❓ Can an attack happen during sleep?

Yes. In rare cases, an attack may start suddenly during sleep or rest without warning.

❓ Does the patient need to stay in the hospital permanently?

No. The patient is usually completely normal between attacks and can live a normal life. However:

Regular medical follow-up is required
The patient must be ready to go to the hospital immediately if early signs of an attack appear

❓ Is the disease very rare?

Yes. It is considered a very rare disease worldwide, which is one of the reasons why it is often difficult to diagnose early or identify correctly.

Types of Systemic Capillary Leak Syndrome (SCLS)

SCLS is not classified into many complex subtypes like some other diseases. Instead, it is practically divided into two main types based on the cause:

1. Primary (Idiopathic) SCLS

Also known as Clarkson’s disease, this is the most common and characteristic form.

Key features:

The exact cause is unknown
It is believed to be related to immune system dysfunction
Many patients have abnormal proteins in the blood called M-protein (monoclonal gammopathy)
It appears as recurrent episodes of fluid leakage from blood vessels

This is considered the classic, rare, and most severe form of SCLS.

2. Secondary Capillary Leak Syndrome

This type occurs as a result of an underlying condition or clear trigger.

Common causes include:

Severe infections such as sepsis or viral illnesses
Certain viral diseases like dengue fever
Some medications or immunotherapies
Certain cancers or blood disorders
Severe systemic inflammation

In this type, capillary leak is a symptom of another disease rather than a standalone disorder.

Causes of Systemic Capillary Leak Syndrome (SCLS)

Systemic Capillary Leak Syndrome (SCLS) is a very rare condition in which there is a sudden leakage of fluids and proteins from tiny blood vessels (capillaries) into surrounding tissues. This leads to a sudden drop in blood pressure, swelling, and potentially serious complications.

What causes SCLS?

The exact cause is still not fully understood, but several possible factors have been identified:

1. Immune system dysfunction

Research suggests an abnormal immune response in which the body may mistakenly affect the blood vessel lining, increasing its permeability and causing fluid leakage.

2. Abnormal blood proteins

Many patients have an abnormal protein called M-protein (monoclonal gammopathy).
This does not necessarily indicate cancer, but it reflects an abnormal immune protein production.

3. Viral or bacterial infections

Some infections may trigger episodes, such as:

Severe colds
Viral infections
Respiratory tract infections

In these cases, infection acts as a trigger rather than a permanent cause.

4. Immune or inflammatory triggers

Certain factors may trigger attacks, such as:

Severe physical stress
Dehydration
Rare reactions to medications or vaccines
Intense emotional or physical stress

5. Possible genetic predisposition

In very rare cases, a genetic predisposition is suspected, but this has not been definitively proven.

Symptoms of Systemic Capillary Leak Syndrome (SCLS)

SCLS usually appears as sudden episodes with rapidly progressing and severe symptoms, often requiring emergency medical care.

Main symptoms:

1. Sudden drop in blood pressure

One of the most dangerous symptoms, which may lead to:

Severe dizziness
Fainting (loss of consciousness)
Shock in severe cases

2. Sudden swelling (edema)

Often appears in:

Hands and feet
Sometimes the face

This occurs due to fluid leaking from blood vessels into tissues.

3. Rapid weight gain

Can occur within hours or days due to:

Fluid accumulation outside blood vessels

4. Intense thirst and dehydration

Caused by loss of fluid from blood vessels as the body tries to compensate.

5. Muscle or body pain

The patient may feel:

General body pain
Heaviness or discomfort due to reduced blood flow to tissues

6. Severe weakness and fatigue

Including:

Extreme tiredness
Difficulty standing or moving for long periods

7. Reduced urination

Occurs due to decreased blood flow to the kidneys and may indicate worsening condition if it persists.

8. Increased blood viscosity (hemoconcentration)

Due to plasma loss from blood vessels, leading to:

Concentrated blood components
Increased risk of blood clots in some cases

Diagnosis of Systemic Capillary Leak Syndrome (SCLS) / Clarkson’s Disease

Diagnosing Systemic Capillary Leak Syndrome (SCLS), also known as Clarkson’s disease, is relatively difficult due to its rarity and because its symptoms resemble other severe conditions such as septic shock or severe allergic reactions.
Therefore, diagnosis mainly depends on combining the full clinical picture and ruling out other diseases.

First: Medical history (the most important step)

The doctor asks about symptoms such as:

Recurrent sudden episodes of very low blood pressure
Rapid swelling of the body or limbs
Sudden weight gain over a short period
Recent infection or physical stress before attacks
Previous similar episodes

Recurrent attacks are one of the strongest indicators of SCLS.

Second: Laboratory tests during an attack

Key findings may include:

1. Complete blood count (CBC):

Increased blood concentration (hemoconcentration)
High hematocrit levels

2. Albumin and proteins:

Low blood albumin due to leakage into tissues

3. Kidney function tests:

May be affected due to reduced blood flow

4. Electrolytes:

Possible imbalance in sodium and potassium levels

Third: Blood protein analysis

A test is done to detect M-protein (monoclonal gammopathy), which is present in many patients with classic SCLS.

The presence of this protein does not mean cancer, but it is a supportive diagnostic marker.

Fourth: Clinical examination

Findings usually include:

Severe unexplained low blood pressure
Generalized swelling with fluid loss from blood vessels
No clear cause such as infection or allergy

Fifth: Excluding other diseases (very important)

Doctors must rule out similar conditions such as:

Sepsis (infectious shock)
Anaphylaxis (severe allergic reaction)
Heart or kidney failure
Advanced liver disease

Treatment of SCLS (Clarkson’s Disease)

Treatment is divided into two main parts:

Acute attack management
Preventive treatment

First: Treatment of acute attacks (Emergency phase)

Acute attacks are medical emergencies and usually require ICU care.

1. Careful fluid replacement

Because blood pressure drops sharply:

IV fluids are given
Albumin may be used

⚠️ Fluids must be carefully controlled to avoid overload during recovery.

2. Vasopressors (blood pressure support)

Used in severe hypotension:

Norepinephrine
Sometimes epinephrine

3. Respiratory support

Oxygen therapy
Mechanical ventilation in severe cases

4. Close monitoring

Includes:

Continuous blood pressure monitoring
Urine output measurement
Kidney function tracking
Electrolyte monitoring

⚠️ Diuretics are usually avoided early as they may worsen dehydration.

Second: Preventive treatment

1. IVIG (Intravenous Immunoglobulin)

Most effective current treatment
Given monthly in many cases
Reduces frequency and severity of attacks
Considered first-line therapy

2. Other medications (less commonly used today)

Theophylline: helps stabilize blood vessels
Terbutaline: reduces capillary leakage (limited use due to side effects)

3. Supportive medications

Corticosteroids: uncertain benefit
Immune-regulating drugs depending on case

4. Management of associated findings

If M-protein is present:

Usually no direct treatment required
Regular monitoring is sufficient

❌ Is there surgery for SCLS?

No. There is no surgical treatment for SCLS because it is a functional disorder of blood vessels, not a structural one.

However, ICU procedures may be used for support, not cure:

Supportive procedures:

Central venous catheter for fluids and medications
Arterial line for continuous blood pressure monitoring
Mechanical ventilation if needed
ECMO in extremely severe cases

These are life-saving supports, not surgical cures.

Recovery time after an attack

Acute recovery phase:

24 to 72 hours
May extend to 4–7 days in severe cases

During this phase:

Blood pressure improves
Urine output increases
Swelling decreases

Full recovery:

2–4 weeks (moderate cases)
6–8 weeks (severe cases)

Prevention of SCLS (Clarkson’s Disease)

There is no guaranteed prevention, but risk reduction is possible.

1. Avoid triggers

Infections:

Frequent handwashing
Early treatment of infections
Vaccination (with medical advice)
Avoid crowded places during outbreaks

Physical stress:

Avoid extreme exertion
Get enough rest

Medications:

Inform doctors about all medications
Avoid immune-triggering drugs without supervision

2. Maintain fluid balance

Drink enough water
Avoid dehydration
Monitor general health

3. Regular medical follow-up

Specialist monitoring (immunology or hematology)
Routine tests
Early detection of warning signs

4. Preventive therapy

IVIG (most important preventive treatment)
Other vascular-stabilizing drugs in selected cases

5. Early recognition of symptoms

Watch for:

Unusual fatigue
Sudden mild swelling
Dizziness or low blood pressure

Early intervention greatly reduces severity.