Capillary leak syndrome overview

# Overview
Capillary leak syndrome is a rare medical condition characterized by self-reversing episodes during which the endothelial cells which line the capillaries are thought to separate for a few days, allowing for a leakage of fluid from the circulatory system to the interstitial space, resulting in a dangerous hypotension, hemoconcentration, and hypoalbuminemia. It is a life-threatening illness because each episode has the potential to cause damage to, or the failure of, vital organs due to limited perfusion. It is often misdiagnosed as polycythemia, polycythemia vera or sepsis.

# Historical Perspective
The syndrome was first described by B. Clarkson in 1960, after whom it was later informally named. Beyond numerous case reports published since then, two comprehensive reviews of clinical and research experience were published in 2010.

# Pathophysiology
The pathogenesis of capillary leak syndrome remain unclear, however, cytokines, vascular endothelial growth factor (VEGF), leukotrienes, and complement play an important role.   During each episode of hyperpermeability of the vasculature, there is an increase of interleukin 2 receptor-positive peripheral blood M-cell count, as well as apoptosis of the endothelial cells.

# Causes
Capillary leak syndrome may be a result of various diseases, and an adverse effect of numerous drugs.
Conditions associated with capillary leak syndrome include sepsis, engraftment syndrome, differentiation syndrome, ovarian hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral hemorrhagic fevers, autoimmune disease, snakebite envenomation, and ricin poisoning.
Drugs associated with capillary leak syndrome include Acitretin, Aldesleukin, Denileukin diftitox, Filgastrim, Oprelvekin, Sargramostim, tbo-filgrastim, gemcitabine, and monoclonal antibodies.

# Differentiating Capillary leak syndrome from other Diseases
As capillary leak syndrome has overlapping clinical and laboratory findings with various other conditions, it should be considered as the diagnosis of exclusion. Some common ones include Adrenal insufficiency, Anaphylaxis, Carcinoid Syndrome, Chronic Heart Failure, Enteropathy, Gleich syndrome, Hereditary angioedema, Inferior vena cava syndrome, Mastocytosis, Nephrotic syndrome, Ovarian hyperstimulation syndrome, Pancreatitis, Pheochromocytoma, Primary amyloidosis, Sepsis and Toxic shock syndrome. Some other conditions that should be considered as a differential diagnosis include Differentiation syndrome, Engraftment syndrome, Hemophagocytic lymphohistiocytosis, Viral hemorrhagic fevers, Snakebite envenomation, Ricin poisoning, as well as multiple autoimmune conditions.

# Epidemiology and Demographics
Between 1960 to 2006, hundred cases of systemic capillary leak syndrome were reported in the world literature.
Capillary leak syndrome has been described in children, however, it is sporadic and is diagnosed most often in previously healthy, middle-aged, Caucasian adults (median age  S.D.: 45  15 yrs; age range 5 months to 74 years).
Based of 107 cases of capillary leak syndrome where information was available, 57% of the individuals were male.

# Risk Factors
Independent risk factors for capillary leak syndrome in neonates include respiratory distress syndrome, sepsis, cold injury syndrome, and hyperglycemia. Condition with monoclonal or M protein detected in the blood as well as autoimmune diseases are risk factors for the development of capillary leak syndrome.  Because of the rarity of the disease there are pending investigations pertaining to the underlying cause.

# Natural History, Complications and Prognosis
Capillary leak syndrome may present as an acute or chronic phase.  The acute phase can be further subdivided into the capillary leak phase and the recruitment of interstitial fluid.
Capillary leak syndrome is associated with the following complications compartment syndrome, pulmonary edema, end-organ damage leading to multiorgan failure, arrhythmias, pericardial effusion, myocardial edema, pancreatitis, acute deep venous thrombosis, acute renal failure, rhabdomyolysis, pleural effusion, and acute ischemic stroke.
Mortality is reported in 21% of the 57 cases described. However, better management of this condition has recently led to lower mortality. Prognosis can be determined according to the SCLS Severity Scale which describes  the condition according to grades.

# Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Other Diagnostic Studies

# Treatment
Medical Therapy | Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies