About Chronic Spontaneous Urticaria
Understanding CSU is the first step toward effective management and finding relief.
What is Chronic Spontaneous Urticaria?
Chronic Spontaneous Urticaria (CSU) is a condition characterized by the spontaneous appearance of hives (wheals), angioedema, or both for 6 weeks or longer, without an identifiable external trigger.
CSU affects approximately 1% of the global population at some point in their lives. It can occur at any age, but most commonly affects adults between 20 and 40 years old, with women being affected twice as often as men.
Unlike other forms of urticaria that are triggered by specific stimuli (such as heat, cold, or pressure), CSU occurs without specific external triggers, making it particularly challenging to identify its cause and manage effectively.
CSU Symptoms
CSU presents with distinct physical symptoms that can significantly impact quality of life.
Hives (Wheals)
- Raised, red or skin-colored welts with clear edges
- Intense itching
- Vary in size from a few millimeters to several inches
- Can appear anywhere on the body
- Individual hives typically resolve within 24 hours, but new ones may continue to appear
Angioedema
- Swelling of deeper layers of skin, particularly around eyes, lips, hands, feet, or genitals
- Sensation of burning or pain rather than itching
- May take up to 72 hours to resolve
- Occurs in about 40-50% of people with CSU
Causes & Mechanisms
While the exact cause of CSU is often difficult to identify, researchers have identified several mechanisms that may contribute to the condition.
Autoimmune Mechanisms
Approximately 30-50% of CSU cases are believed to have an autoimmune basis. In these cases, the immune system produces antibodies against the body's own tissues, particularly:
- IgE autoantibodies - Antibodies that target the body's own proteins
- Anti-FcεRI autoantibodies - Antibodies that target receptors on mast cells
- Anti-IgE autoantibodies - Antibodies that target other antibodies
These autoantibodies can trigger mast cells to release histamine and other inflammatory mediators, leading to the characteristic symptoms of CSU.
Other Potential Contributing Factors
Mast Cell Abnormalities
Some individuals with CSU may have hyperreactive mast cells that release mediators more easily than normal.
Associated Health Conditions
CSU has been associated with other autoimmune conditions, including thyroid disorders, rheumatoid arthritis, and celiac disease.
Genetic Predisposition
Some genetic factors may increase susceptibility to developing CSU.
Stress and Psychological Factors
Emotional stress can exacerbate symptoms in many patients with CSU.
Diagnosis
Diagnosing CSU involves a thorough evaluation to rule out other potential causes of recurrent hives.
Medical History
Your doctor will review your complete medical history and ask detailed questions about your symptoms, including onset, duration, frequency, and potential triggers.
Physical Examination
A thorough examination to assess the appearance, distribution, and characteristics of your hives and any associated angioedema.
Laboratory Tests
Blood tests may include complete blood count, erythrocyte sedimentation rate, thyroid function tests, and autoantibody screening.