Studies in the Pathogenesis of Systemic Capillary Leak Syndrome

This study is currently recruiting participants. (see Contacts and Locations)
Verified January 2014 by National Institutes of Health Clinical Center (CC)
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:
First received: July 9, 2009
Last updated: September 3, 2014
Last verified: January 2014


  • Systemic Capillary Leak Syndrome (SCLS) is a disorder of unknown cause characterized by episodes of life-threatening drop in blood pressure and leakage of fluids into tissues. The outcome from an episode of SCLS may be mild and resolve on its own, or may be severe and result in death. Although SCLS likely involves abnormalities in the cells lining blood vessels, the specific cause(s) of this disorder are not known.
  • The treatment of choice for an acute SCLS episode is intravenous fluids and drugs such as norepinephrine (adrenaline), which are given to keep blood pressure at a level that will maintain vital organ function. This may be followed by a course of intravenous steroids. Currently, there is no cure or long-term effective preventive therapy for patients who experience recurrent episodes of SCLS.
  • This protocol is focused on understanding what causes SCLS with the hope that research findings will lead to the design of safe and more effective treatments.


- To investigate mechanisms that may cause Systemic Capillary Leak Syndrome.


  • Patients between 16 and 65 years of age who have been diagnosed with SCLS.
  • Patients must have a documented history of at least one episode of SCLS with all three of the following documented on at least one occasion: low blood volume, low blood pressure without cause, or evidence of protein leakage during the episode. Patients will also need to provide a letter of a referral from a treating physician.


  • Patients will be evaluated at the National Institutes of Health (NIH) for approximately 4 to 5 days on an inpatient basis, and will undergo the following procedures:

    • Medical history and physical examination.
    • Blood samples for evaluation and research purposes, as well as possible genetic testing.
    • Apheresis procedure to obtain a larger volume of blood cells for research.
    • Bone marrow biopsy, if medically indicated.
    • Other medically indicated tests, such as skin tests to check for possible allergic reactions.
  • Patients who have a capillary leak episode while at NIH will be treated with the standard of care for treating SCLS.
  • Patients will be discharged from the protocol 2 weeks after the NIH visit.
  • Relatives (who are between 1 and 80 years of age) of SCLS patients may also be asked to provide blood samples for the study.

Systemic Capillary Leak Syndrome

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Studies in the Pathogenesis of Systemic Capillary Leak Syndrome

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 210
Study Start Date: July 2009
Detailed Description:

The systemic capillary leak syndrome (SCLS, Clarkson syndrome) is an exceedingly rare disorder of unknown cause characterized by chronic edema or acute transient, severe episodes of hypotension, hypovolemia, and oliguria. Severe edema results from leakage of fluid and macromolecules (200-900 kDa) into tissues. Acute SCLS episodes carry a high morbidity and mortality (25-30%). Only 150 cases have been reported worldwide since 1960, although the disease may be underdiagnosed due to the nonspecific nature of the presenting signs and symptoms and the considerable overlap with other shock syndromes including sepsis, anaphylaxis, and angioedema. Approximately 85% of such individuals have a monoclonal gammopathy of unknown significance (MGUS), but the relationship of this finding to disease pathogenesis is unclear. This protocol will focus on the pathogenesis of SCLS. Subjects with documented episodes of capillary leak will be evaluated in order to correlate both clinical and laboratory features that are typical of SCLS. The goal is to identify biological factors and/or genetic and molecular events that may predispose to SCLS episodes. We plan to enroll up to 210 subjects, family members and healthy volunteers in this study. We anticipate that our findings may be a first step toward the development of new targeted therapies.


Ages Eligible for Study:   16 Years to 80 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Subject with SCLS must be at least 16 years of age.

Diagnosis or suspected diagnosis of Systemic Capillary Leak Syndrome by a physician or documented history of capillary leak as characterized by one or more of the following:

  1. Hypotension (systolic blood pressure typically less than 90 mm Hg or diastolic blood pressure less than 60 mm Hg) or associated symptoms of hypotension (e.g., hypotonia [collapse], lightheadedness or syncope, incontinence, increased thirst)
  2. Laboratory evidence of hemoconcentration (e.g., hemoglobin levels above the normal range [typically greater than17 g/dL], elevated leukocyte counts).
  3. Clinical evidence of fluid extravasation (e.g. edema) and/or laboratory evidence of protein extravasation such as serum hypoalbuminemia (less than 3.5 g/dL) either chronically or during an acute hypotensive episode.

    Letter of referral, with copies of pertinent medical history and laboratory studies, from prospective study subject s referring physician. Patients may self-refer, but a letter of referral from primary physician is still required.

    Ability to give informed consent, or parent or guardian able to give informed consent.

    Willing to donate blood for sample storage to be used for future research.


    Willing to donate blood for sample storage to be used for future research.

    Subjects must be at least 18 years old.

    Able to give informed consent.


    Presence of conditions which in the judgment of the investigator or the referring physician may put the subject at undue risk for travel (including frequent episodes of severe capillary leak, symptoms not preventable by pre-medication, acute infection, severe thrombocytopenia [minimum platelet count of 30,000/microL], or significant cardiovascular disease)

    Any condition that in the view of the principal investigator would make the subject unsuitable for enrollment in this study

    There is an identified cause for your hypotensive episodes and/or tissue swelling.


    Presence of conditions which in the judgment of the investigator may put the subject at undue risk

    Any condition that in the view of the principal investigator would make the subject unsuitable for enrollment in this study


    No relatives or healthy volunteers below the age of 18 will be enrolled. However, children (age < 16 years) with SCLS will be excluded from this study.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00936325

Contact: Lauren M Long, R.N. (301) 451-9921
Contact: Kirk M Druey, M.D. (301) 435-8875

United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike Recruiting
Bethesda, Maryland, United States, 20892
Contact: For more information at the NIH Clinical Center contact Patient Recruitment and Public Liaison Office (PRPL)    800-411-1222 ext TTY8664111010   
Sponsors and Collaborators
Principal Investigator: Kirk M Druey, M.D. National Institute of Allergy and Infectious Diseases (NIAID)
  More Information

Additional Information:
Publications: Identifier: NCT00936325     History of Changes
Other Study ID Numbers: 090184, 09-I-0184
Study First Received: July 9, 2009
Last Updated: September 3, 2014
Health Authority: United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):
Systemic Capillary Leak Syndrome

Additional relevant MeSH terms:
Capillary Leak Syndrome
Pathologic Processes
Vascular Diseases
Cardiovascular Diseases processed this record on October 16, 2014