Capillary leak syndrome happens when fluid leaks from your small blood vessels into surrounding tissues. It requires immediate treatment to prevent a drop in blood pressure and other serious complications. Capillary leak syndrome can’t be cured, but you can reduce episodes by taking medications as prescribed.
Capillary leak syndrome happens when plasma (the liquid part of your blood) leaks out of tiny blood vessels (capillaries). The fluid leaks into muscles, tissues, organs and body cavities (spaces that hold organs).
Capillary leak syndrome attacks, or episodes, can occur several times a year or only once. If capillary leak syndrome isn’t treated promptly, your blood pressure drops rapidly, leading to organ failure and even death.
Though there’s no cure for capillary leak syndrome, it’s important to get prompt medical treatment to manage symptoms. You may be able to prevent future episodes of systemic capillary leak syndrome with regular use of medications or infusions.
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There are two major types of capillary leak syndrome:
Systemic capillary leak syndrome is a rare disorder that affects less than 500 people worldwide. Systemic capillary leak syndrome mainly happens in middle age and is very rare in children. That said, the incidence might be higher, as people with systemic capillary leak syndrome may often be misdiagnosed.
Secondary capillary leak syndrome can happen in people of any age. Certain infections, diseases and medications may lead to capillary leak syndrome.
There are three stages to a capillary leak syndrome episode:
The cause of systemic capillary leak syndrome is unknown. Researchers suspect that an immune system response to an illness or infection may cause the condition.
Sepsis (a life-threatening complication of infection) most commonly causes secondary capillary leak syndrome. Other conditions that cause capillary leak syndrome include:
Certain medications, including the chemotherapy drugs gemcitabine (Gemzar®) and tagraxofusp (Elzonris®), may also cause secondary capillary leak syndrome.
Symptoms usually begin one or two days before a capillary leak syndrome attack. This is called the prodromal phase. These symptoms may include:
During a capillary leak syndrome episode (called the leak or resuscitation phase), symptoms may vary from person to person. Common symptoms can include:
Healthcare providers diagnose capillary leak syndrome by asking about your health history and doing a physical examination. They’ll check your blood pressure to see if it’s low.
Healthcare providers may also need to exclude other conditions before they can diagnose capillary leak syndrome. They may order blood tests to look for:
They may also do a blood test to look for abnormal immunoglobin protein (monoclonal gammopathy, or M protein). People with capillary leak syndrome may have abnormal M protein in their blood.
There isn’t a cure for capillary leak syndrome. Healthcare providers focus on managing symptoms and preventing complications.
During a capillary leak syndrome episode, healthcare providers try to control blood pressure to maintain blood flow to your organs. They also try to prevent excess swelling and fluid buildup. They may use:
You’ll usually be hospitalized during an episode. During treatment, your healthcare provider will constantly monitor your vein and arterial pressure to ensure that too much fluid doesn’t build up in your body. Excess fluid can lead to other complications, including pulmonary edema (excess fluid in your lungs) and sudden cardiac arrest.
After the capillary leak syndrome attack (post-leak phase or recruitment phase), your healthcare provider may use a diuretic to decrease the fluid. A diuretic is a pill that helps your body get rid of water and salt through increased urine.
You can’t prevent systemic capillary leak syndrome from developing. Once you’ve had an attack, you know you have the condition.
Regular use of medications or infusions may help prevent future episodes and reduce their severity. These treatments may include:
Systemic capillary leak syndrome can usually be managed with preventive treatments. Treatments generally work better when people are diagnosed earlier and have fewer complications. Serious complications due to capillary leak syndrome may include:
See your healthcare provider immediately if you think you’re experiencing the start of a capillary leak syndrome episode. They can help manage your symptoms and keep you more comfortable.
A note from Cleveland Clinic
Capillary leak syndrome is a condition where plasma leaks from your capillaries into other tissues of your body. Capillary leak syndrome can happen once or many times. Complications of untreated capillary leak syndrome can be serious. The sooner you’re diagnosed with capillary leak syndrome and begin treatment, the better your chances of a positive outcome.
Last reviewed by a Cleveland Clinic medical professional on 04/07/2022.
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