Urticaria or Hives
Urticaria affects up to 25% of people at some point in their lives. Up to 3% of people have chronic idiopathic urtcaria, which means that the urticaria has been occurring for more than 6 weeks, and has no identifiable cause.
There are a number of possible triggers of urticaria, but 80-90% of cases of chronic urticaria (uricaria that has been occurring for at least 6 weeks) are idiopathic, which means that there is no identifiable trigger.
In cases that do have a trigger, there are a number of possible triggers including:
- Infections (viral and possibly bacterial or fungal)
- Other chronic medical illnesses (such as lupus, thyroid disease, and even cancer)
- Pressure to the skin
- Trauma to the skin
- Sun exposure
As many as 40-60% of people with chronic idiopathic urticaria have an autoimmune cause of their urticaria. When part of the patients own blood is injected into the top layer of his/her skin, a hive occurs, suggesting that there is something in the patients own blood that causes a hive to occur in the skin. Some of these patients have antibodies that bind to receptors on some of the skin cells. There antibodies probably trigger the cells to release histamine, which causes a hive.
We do not currently know of any way to get rid of these antibodies, so for now, these patients are treated in the same way as any other patients with chronic idiopathic urticaria. However, future research may lead to the discovery of a new way to treat these patients who have autoimmune antibodies that cause urticaria.
There is currently no known way to permanently cure chronic idiopathic urticaria, but we do know that most cases are characterized by periodic flare-ups with symptom-free intervals between , and most of the time the urticaria will eventually "burn-out" and never come back, although this may not happen until many months or even years have gone by.
In cases where a trigger can be identified, the best way to treat urticaria is by avoidance of the trigger.
In cases where no trigger can be identified (80-90% of longstanding urticaria), there are some medications which can help relieve, and even prevent symptoms.
Antihistamines are the most helpful. Over-the-counter antihistamines, such as Benadryl, are helpful, but often cause side effects, such as drowsiness. Some of the newer prescription antihistamines can help without causing any side effects.
Some cases might require a short course or a shot of steroid medication, but long term treatment with steroids is usually avoided because of possible harmful side effects. However, in severe cases that do not respond to the usual medications, long term treatment with low doses of steroids can be considered.
Disease Modifying Drugs
Some of the disease modifying drugs that are used for connective tissue diseases (such as lupus and rheumatoid arthritis) have been found to be helpful in some patients with severe chronic urticaria, but these drugs are frequently associated with side effects.
Autoimmune Antibodies found in Urticaria and Treatment
Projects currently undergoing include studies focusing on the autoimmune antibodies found in urticaria and treatment of urticaria with newer medications. The autoimmune antibody study aims at learning more about the biology of urticaria by studying the antibodies produced in some of the patients, and the receptors they bind to, on the skin cells. Patients with longstanding urticaria, who do not have any identifiable trigger for their symptoms, are enrolled in the study on a volunteer basis and a sample of blood is drawn for investigative purposes.
Treatment Response to Thyroxine
The other main project underway aims at studying the treatment response to Thyroxine (thyroid hormone), in patients who do not respond to conventional therapy, such as antihistamines. It is hypothesized on the basis of some previous investigations, that at least some patients, especially those who have antibodies against the thyroid gland, may benefit from treatment with thyroxine. Enrollment in the study is for 16 weeks, on a volunteer basis, for patients who fulfill the inclusion criteria.