What does CLS stand for?

CLS stands for Capillary Leak Syndrome. Capillary leak syndrome is a disease associated with generalized edema. The disease occurs at low frequency in the population and can cause serious complications. In some cases, capillary leak syndrome is also known as Clarkson syndrome. The cause of capillary leak syndrome is usually that the capillaries are too permeable for plasma and associated proteins to enter what is known as the interstitium.

What is Capillary Leak Syndrome?

The capillary leak syndrome was first described in 1960 by the American physician Clarkson. For this reason, the condition is sometimes called Clarkson syndrome. Basically, it is a comparatively rare disease. See AbbreviationFinder for abbreviations related to CLS.

Up to 2002, only 57 patients suffering from capillary leak syndrome were documented. It turns out that the people affected were on average 46 years old. The ages ranged from nine to 67 years. No gender difference was found, instead capillary leak syndrome occurs with equal frequency in males and females.

The disease can even affect childhood patients. In most English-speaking countries, capillary leakage syndrome is referred to as capillary leakage syndrome, from which the international abbreviation CLS is derived.


So far, the exact causes of capillary leak syndrome have not been sufficiently researched, so that certain factors and mechanisms of the etiology of the disease are unknown. Some speculate that specific types of cytokines are responsible for causing the capillaries to become more permeable.

For example, the substance interleukin-2 is up for discussion as a potential factor. Other physicians assume that the planned death of the cells (medical term apoptosis) or so-called leukotrienes are involved in the development of the capillary leak syndrome. In particular, the focus is on the apoptosis of endothelial cells.

There are also speculations about a genetic component of the capillary leak syndrome. This point of view is mainly supported by the fact that hereditary strains from the family were identified in one patient. For this reason, it seems likely that the condition, or at least a predisposition to capillary leak syndrome, is inherited.

In addition, the majority of those affected have a monoclonal gammopathy. In most cases, this is the subform IgG. For this reason, some medical professionals suspect that this monoclonal gammopathy is involved in the development of capillary leak syndrome. However, mutated plasma proteins do not accumulate within the interstitium.

Symptoms, Ailments & Signs

In the context of capillary leak syndrome, there are intermittent hypovolemic shocks that are severe and extremely severe. Basically, these are so-called volume deficiency shocks, which are accompanied by edema of a generalized nature. In addition, people suffering from capillary leak syndrome suffer from hypotension of the arteries associated with thickening of the blood.

The cause of this thickening is that plasma water is lost from the blood. Hypoalbuminemia is also involved in its development. As part of this phenomenon, the proportion of the protein albumin in the blood plasma is reduced. The cause of these symptoms is the greatly increased permeability of the capillary blood vessel walls. As a result, blood plasma passes into the interstitium area.

Basically, each interval of capillary leak syndrome is divided into two sections. In the initial phase, the affected patients suffer from general symptoms such as nausea and pain in the abdominal area. On the other hand, hypotension of an arterial nature and generalized edema develop.

These symptoms last for a few days. A feared complication during this time is a collapse of the cardiovascular system. There is also a risk that the kidneys will fail or the tubule will be damaged because the blood volume is too low. In some cases there is also a so-called rhabdomyolysis, in which the striated fibers dissolve within the muscles.

During the subsequent phase, the liquid substance that has leaked from the capillaries moves. As a result, polyuria develops, with patients excreting excessive amounts of urine. In addition, the formation of edema in the lungs or a so-called water lung is possible.

Diagnosis & course of disease

The diagnosis of capillary leak syndrome focuses on the clinical symptoms present. It is particularly important to take a thorough anamnesis together with the patient. In the subsequent phase of the examination, the doctor treating you analyzes the individual symptoms. For example, blood and urine tests are used. The blood values ​​often provide important indications of the presence of capillary leak syndrome.


Capillary leak syndrome can cause significant disruption and complications in the patient. For this reason, treatment of the affected person is usually necessary. In most cases, the patients first suffer from abdominal pain and then from nausea. It is not uncommon for capillary leak syndrome to continue to lead to cardiovascular problems, which can lead to a complete breakdown.

Renal insufficiency can also occur, which can be life-threatening for the person concerned. The patient is dependent on a donor kidney or has to undergo dialysis. Quality of life is significantly reduced by capillary leak syndrome. If necessary, the life expectancy can also be reduced.

Unfortunately, there is no direct treatment for capillary leak syndrome, so there are no complications. The symptoms can possibly be reduced with the help of medication. However, a positive course of the disease cannot be guaranteed. It is not uncommon for the capillary leak syndrome to also lead to psychological complaints, so that those affected are dependent on psychological treatment. Depression and other mental upsets can be avoided.

When should you go to the doctor?

Circulatory problems must be examined and treated by a doctor at all ages. Since in severe cases they can lead to a collapse and early death, a doctor should be consulted at the first irregularities in the cardiovascular system. If water retention is noticed in the legs or other parts of the body, there is also cause for concern. A doctor should be consulted to clarify the symptoms.

Breathing noises or disturbances in breathing activity can indicate water in the lungs. The affected person should consult a doctor to determine the cause of the impairments. If the symptoms generally increase in type and extent, a doctor’s visit is required as soon as possible. In case of dizziness, nausea, vomiting or pain in the abdominal region, a doctor should be consulted. If there is a general feeling of illness, inner weakness or malaise, further investigations should be initiated. If malfunctions occur, a doctor must be consulted immediately.

There is a risk of organ failure without medical care. The kidneys are particularly at risk with capillary leak syndrome. A drop in blood pressure, a reduced heartbeat or circulatory disorders indicate irregularities and other diseases. If you experience numbness in your limbs or cold fingers and toes, see a doctor.

Treatment & Therapy

Since very few cases of capillary leak syndrome have been observed to date, treatment methods are relatively limited. Because there is a lack of corresponding research studies and results on the effectiveness of various therapeutic approaches. Basically, there is currently no standard treatment for capillary leak syndrome.

The active substances theophylline and terbutaline were tested for prophylaxis, some of which have shown good effectiveness. If the capillary leak syndrome has a chronic course in individual cases, treatment with glucocorticoids is promising. These include, for example, diuretic agents.

Outlook & Forecast

Self-help for capillary leak syndrome must always be closely coordinated with the treating physicians due to the risk of a new hypovolemic shock.

The first measure should be a change from the previous diet plan to a healthy and balanced diet. Since the layman often lacks the experience for this, it is advisable to get the support of a nutritionist who is familiar with the disease at hand. Because a well-chosen diet strengthens the immune system on the one hand, but can also reduce the onset of symptoms such as nausea or pain and thus contribute to an improvement in life.

In addition, avoiding stress, regular moderate exercise, and plenty of rest help unload the body between two shock reactions. It is advisable to keep a complaint diary in which new symptoms and other abnormalities are noted. This ensures that the attending doctor is always informed about the overall condition during the close examinations. This makes it easier for him to adapt the medication to individual needs and to prevent possible further shock reactions as far as possible. Since affected children are not yet able to communicate adequately up to a certain age, it is incumbent on the parents in these cases to pay particular attention to possible new symptoms or abnormalities and to note them down.


No effective methods to prevent capillary leak syndrome have been explored.


Since capillary leak syndrome is a serious and serious condition, it should be evaluated by a doctor at the very first signs and symptoms. As a rule, self-healing is not possible either, so that those affected are always dependent on a medical examination and treatment in order to alleviate the symptoms over the long term. In most cases, direct aftercare measures are severely limited or are not available to the person concerned.

As a rule, those affected by capillary leak syndrome are dependent on taking various medications. It is always important to ensure that the medication is taken regularly and that the correct dosage is used in order to prevent further complications. Likewise, if you have any questions or are unclear, you should always consult a doctor immediately.

A healthy lifestyle with a balanced diet can have a positive effect on the progression of capillary leak syndrome, so a nutrition plan can be drawn up by a doctor that should be followed. In many cases, contact with other patients with the syndrome is also useful, as this can lead to an exchange of information.

You can do that yourself

For capillary leak syndrome, treatment focuses on relieving symptoms. In the case of some symptoms, the patients can support the drug therapy with their own measures.

Rest and bed rest are recommended first. The intermittent shock reactions place an enormous strain on the body. For this reason, those affected need a lot of rest, accompanied by moderate exercise, avoidance of stress and regular medical examinations. Relatives and parents of affected children should keep a close eye on the patient so that they can react quickly in the event of another hypovolemic shock. The drug treatment must be regularly readjusted to the current state of health of the person concerned. The person concerned should keep a complaints diary in which he records unusual symptoms. This makes it easier for the doctor to adjust the medication.

Finally, the recovery can be promoted by changing the diet. A healthy and balanced diet can reduce initial symptoms such as nausea and pain. In addition, a healthy lifestyle strengthens the immune system. As a result, the intensity and frequency of the shock reactions decrease in the best case. Those affected should also drink a lot to counteract the thickening of the blood.

Capillary Leak Syndrome