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Disease Profile

Systemic capillary leak syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

SCLS; Clarkson disease; Capillary leak syndrome;


Systemic capillary leak syndrome (SCLS) is a condition in which fluid and proteins leak out of tiny blood vessels, into surrounding tissues. This can result in dangerously low blood pressure (hypotension), hypoalbuminemia, and a decrease in plasma volume (hemoconcentration).[1][2] Initial symptoms may include fatigue, nausea, abdominal pain, extreme thirst, and sudden increase in body weight. Episodes of SCLS vary in frequency, with some people having one episode in their lifetime, and others having several per year. The severity also varies, and the condition can be fatal.[2]

In many cases the cause is not known (idiopathic SCLS).[2] Some people with SCLS report having had an infection (such as a virus) before the episode.[3] Some cases of capillary leak are associated with various conditions of the heart, kidney, or liver.[2] Treatment during an episode may involve stabilizing the airway and breathing, and infusion of fluids, medications, or blood products. Periodic infusions or the use of certain medications may be used to prevent future episodes.[2]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Elevated white blood count
High white blood count
Increased blood leukocyte number

[ more ]

Pedal edema
Fluid accumulation in lower limbs
Lower leg swelling

[ more ]

30%-79% of people have these symptoms
Abdominal pain
Pain in stomach
Stomach pain

[ more ]

Watery stool

[ more ]

Low blood pressure
Muscle ache
Muscle pain

[ more ]

Pancreatic inflammation
Pulmonary edema
Excess fluid in lungs
Wet lung

[ more ]

Runny Nose
Weight loss
5%-29% of people have these symptoms
Abnormal renal tubule morphology
Abnormal heart rate
Heart rhythm disorders
Irregular heart beat
Irregular heartbeat

[ more ]

Cardiorespiratory arrest
Multiple myeloma
Inflammation of heart muscle
Swelling or irritation of membrane around heart
Pleural effusion
Fluid around lungs
Renal insufficiency
Renal failure
Renal failure in adulthood

[ more ]

Venous thrombosis
Blood clot in vein


Systemic capillary leak syndrome is diagnosed based on physical examination, laboratory tests, and recurrence of symptoms. Recurring episodes are associated with monoclonal gammopathy in the majority of patients (when an abnormal immunoglobin protein is found in the blood). The diagnosis is supported by ruling out other illnesses with similar symptoms, including secondary capillary leak syndrome or abnormally low levels of protein in the blood (hypoproteinemia).[4][2][5]


There is currently no cure for systemic capillary leak syndrome (SCLS). Treatment for SCLS during an episode is mainly supportive, aiming to stabilize symptoms and prevent severe complications.[3] This may involve stabilizing the airway and breathing, taking certain medications, and/or intravenous (IV) infusion of fluids, medications, or blood products.[2] Some have suggested that IV fluids are not recommended because it may worsen swelling (edema) or increase the risk for other complications.[4] Once a person begins to recover, diuretics are almost always required.[2]

Periodic infusions or the use of certain medications are used to try to prevent future episodes (prophylactic therapy). Having monthly infusions of intravenous immune globulin (IVIG) has been suggested.[2] A study published in 2017 found that preventive treatment with IVIG was the strongest factor associated with survival in people with SCLS.[5] Those who do not improve with IVIG or who cannot tolerate the therapy may have success with theophylline and terbutaline.[2]

Research into how SCLS develops and factors that affect its course are underway, in hopes that a better understanding of SCLS will lead to more effective treatment options and a lower mortality rate.


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Social Networking Websites

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The National Cancer Institute glossary of terms includes an entry for capillary leak syndrome with monoclonal gammopathy. Click on National Cancer Institute to view the definition.
  • Mayo Clinic has an information page on Systemic capillary leak syndrome.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Systemic capillary leak syndrome. Click on the link to view a sample search on this topic.


  1. Dictionary of Cancer Terms: capillary leak syndrome. National Cancer Institute (NCI). https://www.cancer.gov/dictionary?CdrID=426421. Accessed 9/11/2014.
  2. Rajesh A. Idiopathic systemic capillary leak syndrome. UpToDate. May 20, 2016; https://www.uptodate.com/contents/idiopathic-systemic-capillary-leak-syndrome.
  3. Druey KM, Parikh SM. Idiopathic systemic capillary leak syndrome (Clarkson disease). J Allergy Clin Immunol. December 22, 2016; https://www.sciencedirect.com/science/article/pii/S0091674916324605.
  4. Amoura Z. Systemic capillary leak syndrome. Orphanet. November 2012; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=188.
  5. Pineton de Chambrun M, Gousseff M, Mauhin W, et al. Intravenous Immunoglobulins Improve Survival in Monoclonal Gammopathy-Associated Systemic Capillary-Leak Syndrome. Am J Med. June 9, 2017; https://www.ncbi.nlm.nih.gov/pubmed/28602874.

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