Overview
Systemic capillary leak syndrome (SCLS), also known as Clarkson disease or idiopathic capillary leak syndrome, is a rare and potentially life-threatening condition where the tiny blood vessels in your body (called capillaries) suddenly become leaky. When this happens, fluid and proteins from your blood escape into the surrounding tissues, causing your blood pressure to drop dangerously low and your tissues to swell. These episodes, called 'attacks' or 'flares,' can come on suddenly and without much warning. During an attack, the body loses so much fluid from the bloodstream that vital organs — including the kidneys, heart, and brain — may not get enough blood flow. This can lead to shock, organ failure, and in severe cases, death if not treated quickly. Between attacks, most people feel completely normal, which makes this disease especially confusing and difficult to diagnose. Most people with SCLS also have an abnormal protein in their blood called a monoclonal immunoglobulin (usually IgG), though doctors are still working to understand exactly how this is connected. Treatment focuses on preventing attacks using a monthly intravenous medication called IVIG (intravenous immunoglobulin), and managing acute episodes in the hospital with aggressive fluid support and other medications. With proper preventive treatment, many patients can significantly reduce the number and severity of attacks.
Also known as:
Key symptoms:
Sudden, severe drop in blood pressureWhole-body swelling (edema), especially in the arms and legsExtreme fatigue and weakness during attacksFeeling faint or losing consciousnessRapid weight gain over hours due to fluid leaking into tissuesThickening of the blood (hemoconcentration), making it harder for the heart to pumpLow blood albumin levels (a protein that normally keeps fluid in blood vessels)Muscle pain or crampingNausea and abdominal discomfortDecreased urination during an attackRebound swelling after an attack as fluid shifts back into the bloodstream
Clinical phenotype terms (23)— hover any for plain English
Sporadic
Usually appears on its own, not inherited from a parent
Adult
Begins in adulthood (age 18 or older)
Treatments
No FDA-approved treatments are currently listed for Systemic capillary leak syndrome.
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Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Systemic capillary leak syndrome.
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Caregiver Resources
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Social Security Disability
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Questions for your doctor
Bring these to your next appointment
- Q1.Should I start preventive IVIG therapy, and how will we know if it is working?,What are my personal early warning signs, and exactly when should I go to the emergency room?,Can you give me a written emergency protocol to bring to the ER during an attack?,Do I need to be monitored for the monoclonal protein in my blood, and could it develop into a blood cancer?,Are there any known triggers for my attacks that I should try to avoid?,What specialists or centers have the most experience treating SCLS?,Are there any clinical trials or research studies I could participate in?
Common questions about Systemic capillary leak syndrome
What is Systemic capillary leak syndrome?
Systemic capillary leak syndrome (SCLS), also known as Clarkson disease or idiopathic capillary leak syndrome, is a rare and potentially life-threatening condition where the tiny blood vessels in your body (called capillaries) suddenly become leaky. When this happens, fluid and proteins from your blood escape into the surrounding tissues, causing your blood pressure to drop dangerously low and your tissues to swell. These episodes, called 'attacks' or 'flares,' can come on suddenly and without much warning. During an attack, the body loses so much fluid from the bloodstream that vital organs
How is Systemic capillary leak syndrome inherited?
Systemic capillary leak syndrome follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Systemic capillary leak syndrome typically begin?
Typical onset of Systemic capillary leak syndrome is adult. Age of onset can vary across affected individuals.
Which specialists treat Systemic capillary leak syndrome?
4 specialists and care centers treating Systemic capillary leak syndrome are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.