HIVES
Hives (Urticaria) are itchy and raised red eruptions of the skin. They may vary in size and blanch when pressure is applied. An individual hive may last minutes or up to 24 hours and re-occur intermittently in different sites on the body for an indefinite period of time. Hives are due to an immunologic reaction in the skin where histamine is released causing the swelling and itching. When the hives occur deeper into the skin, it causes more swelling referred to as Angioedema.
Over 20% of the population will have hives at least once in their lifetime. Acute hives may occur in any age group and is most often seen in children. These hives are often self-limited or can be controlled symptomatically with antihistamine drugs and avoidance of identifiable triggers.
Chronic hives are more common in adults and persist for more than 6 weeks with no identifiable trigger. 40% have episodes of angioedema, 45% have an autoimmune process associated with anti-thyroid antibodies or high affinity IgE receptor (FceR1) antibody.
Possible Causes of Hives
- INFECTIOUS DISEASE – viral infections (most common cause of acute urticaria), hepatitis, infectious mononucleosis, bacterial, parasitic or fungal infections
- MEDICATIONS – penicillin, other antibiotics, aspirin, insulin, vaccines, allergy injections, morphine, demerol, codeine, etc
- ENVIRONMENTAL ALLERGENS – grass, animal dander or saliva, insect stings, etc
- FOODS – eggs, milk, wheat, soy, peanuts, treenuts, fish, shellfish and other foods
- AUTOIMMUNE or NONINFECTIOUS CAUSES – autoimmune hives (most common cause of chronic hives), collagen vascular disease, malignancy, thyroid disease, hormonal changes
- PHYSICAL AGENTS – cold, heat, sunlight, pressure, vibratory, exercise
- PSYCHOLOGICAL FACTORS – Stress, anxiety
Evaluation and Treatment
Acute hives not associated with angioedema or respiratory distress is usually self limited and evaluation may include testing for possible triggers.
Chronic hives require an extensive evaluation with history, physical exam, allergy testing and laboratory testing for the immune system, liver, kidney, thyroid and collagen vascular diseases. Special tests will be sent for anti-thyroid antibodies and high affinity IgE receptor (FceR1) antibody to look for autoimmune hives. Age appropriate cancer screening is recommended. 55% of patients will not have an identifiable trigger for their hives.
