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May 08, 2006
Urticaria (Hives or Angioedema) info
by SirGan|
Hives, also known as urticaria, is a medical condition which is characterized by raised, red, often itchy circles of various size that appear and disappear on the skin. They are localized superficially. Urticaria is also known as nettle rash or uredo. These red skin patches can range in diameter, they often have a pale border and are causing a severe itchy sensation. They usually appear as a result of the body's adverse reaction to certain allergens or for unknown reasons. Angioedema is a tissue swelling similar to urticaria, but the swelling occurs beneath the skin instead on the surface. It is a much more serious condition. Angioedema is characterized by deep swelling around the eyes and lips and sometimes of the genitals, hands and feet. Angioedema generally lasts longer than urticaria, but the swelling usually goes away in less than 24 hours. This can be a very dangerous condition because, angioedema of the throat, tongue or the lungs can block the airways, causing difficulty breathing and become life-threatening even though this happens really rarely. IncidenceUrticaria affects 15-20% of the general population in the US and around the world. One in five people is experiencing acute hives or angioedema at some time of their life. Hereditary angioedema affects only about 6,000 people in the United States. Incidence rates for acute urticaria are similar for men and women although the chronic urticaria occurs more frequently in women. Types of urticaria and angioedema* Acute UrticariaThis type of hives lasts less than six weeks. The most common causes areo food, o medications, o latex o infections o environmental factors (pollens, chemicals, plants, dander, dust, mold) o emotional stress o insect bites and o some internal disease The most common food that can cause hives includes nuts, chocolate, fish, tomatoes, eggs, fresh berries and milk. Among the most common medications that can cause hives and angioedema are: o Aspirin o Nonsteroidal anti-inflammatory medications o Ibuprofen, high blood pressure medications (ACE inhibitors) or o Pain-killers such as codeine * Chronic Urticaria and AngioedemaHives that are lasting more than six weeks are called the chronic ones. The cause of this type of hives is usually more difficult to identify than that of the acute urticaria and the fact is that it remains unknown in more than 80 percent of patients. Chronic urticaria and angioedema can effect internal organs and can cause symptoms such as shortness of breath, vomiting, and diarrhea. They can also be caused by several other conditions such as: * emotional stress, * heat, * exercise, * chronic medical illness, such as hyperthyroidism, SLE, rheumatoid arthritis * pregnancy * Physical UrticariaThis is the type of hives caused by the direct physical stimulation of the skin such as cold, heat, sun exposure, vibration, pressure, sweating, exercise and others. Most of the experts believe that there is a completely different mechanism behind this type of urticaria. The hives usually occur at the site of direct stimulation and rarely, appear on other skin areas. Most of the hives appear within one hour after the exposure. There are several sub-types of this urticaria and the most common are: * Aquagenic: Reaction to water  * Cholinergic: Reaction to body heat * Cold: Reaction to cold, such as ice, cold air or water * Delayed Pressure: Reaction to standing for long periods, bra-straps, belts * Heat: Reaction to hot food or objects * Solar: Reaction to direct sunlight * Vibration: Reaction to vibration * Adrenergic: Reaction to adrenaline * DermatographismThis is a very common type of urticaria and most of the experts count it into physical urticaria group. Anyone can experience this sometimes in life because this type of hives is considered a normal variant of the skin. This type of hives form after firmly stroking or scratching the skin. Symptoms and signsHivesThe accute hives can last up to six weeks, while chronic hives last more. Hives are raised, red bumps of various sizes that appear on your skin and disappear soon after. They're often itchy and may look similar to mosquito bites. They could be localized all over the body, depending on the place where the allergen was applied. AngioedemaAngioedema is similar to hives, but occurs deeper in the skin. Signs and symptoms of angioedema include large welts or swelling of the skin that may occur in the following locations: * Near your eyes and lips * On your hands * On your feet * On your genitalia * Inside of your throat Hereditary angioedemaHereditary angioedema occurs in about 1 in 100,000 people. These patients lack an effective enzyme, which is associated with swellings of the face, throat or limbs. This type of angioedema is accompanied with several symptoms and the most common are: * Sudden and severe swelling of your face, arms, legs, hands, feet, genitalia, digestive tract and airway * Abdominal cramping as a result of digestive tract swelling * Difficult or obstructed breathing due to swelling of your airway Pathophysiology of the conditionExperts have proven that urticaria is caused by the release of several mediators such as histamine, bradykinins, kallikrein, or acetylcholine, resulting in intradermal edema from capillary and venous vasodilatation and occasional leukocyte infiltration. There are two possible mechanisms that could be responsible for the urticaria and they are: * Immunologic mechanismThis mechanism is explained by the theory that all the manifestations of acute urticaria are caused by immunoglobulin E mediated hypersensitivity with histamine released from mast calls as its primary mediator. It also may be the result of the complement-mediated reactions or specific drug reactions. * Non-immunologic mechanismThere are several theories that tried to explain this type of urticaria. According to some experts, mediators can be released from mast cells without IgE and immunologic reaction. Some people have inherited weakness of the mast cells walls. Physical urticaria can be caused by the direct physical contact and without any immunologic reaction. Risk factorsPerson may be at greater risk of hives and angioedema if he or she has or had: * hives or angioedema before * other allergic reactions * family history of hives or angioedema * family history of hereditary angioedema Diagnosis of urticariaA doctor should ask many questions in an attempt to find the possible cause because, in most cases, this can be very difficult. Since there are no specific tests for hives or the associated swelling of angioedema, testing will depend on your medical history and a thorough examination by your dermatologist. Skin tests may be performed to determine the substance that you are allergic to. There are several lab studies that could confirm the diagnosis and the most common are: * Stool examination for fecal ova, and parasites * Antinuclear antibody titer * Hepatitis B and C screen * Thyroid function tests * Tests for CBC, prostate-specific antigens, and serum calcium Treatment of urticaria and angioedemaThe standard treatment for hives and angioedema is antihistamines, which block the symptom-producing release of histamine. * HistaminesOral antihistamines control itching for the majority of patients with urticaria, but the problem is that they do not affect the underlying cause of the rash. Antihistamines may need to be taken intermittently or continuously until the underlying tendency to urticaria disappears. Some of the most commonly used non-sedating antihistamines are o loratidine, o fexofenadine, o terfenadine, o cetirazine, and o astemizole Patients should also keep in mind that these may be unsuitable during pregnancy. Terfenadine and astemizole may increase the risk of abnormal heart rhythms. * CorticosteroidsFor severe hives or serious types of angioedema, doctors may prescribe an oral corticosteroid drug, most commonly-prednisone, which can help lessen swelling, redness and itching. They stabilize mast cell membranes and inhibit further histamine release. They also reduce the inflammatory effect of histamine and other mediators. * Other medicationsIt is very important to remember that these medications are often ineffective in treating hereditary angioedema. Medications used specifically to treat the hereditary form of this condition on a long-term basis include certain androgens, such as danazol (Danocrine), that help regulate levels of blood proteins. Sometimes, only an urgent medical intervention can save the life of the patient because, in cases of a severe and serious attack of hives or angioedema, patient may need an emergency injection of adrenaline and a trip to the emergency room. Other medications include: o Ultraviolet radiation treatment o Antibiotics and antifungal agents, used to clear an assumed underlying infection or for non-specific anti-inflammatory action. o Immunosuppressive medications o Antifibrinolytic agents o Tricyclic medications such as amitriptyline, nortriptyline and doxepin Self careHere are some of the most useful tips for the future self care of the hives patients: * Avoid irritating affected areas. * Take cool showers. * Reduce your intake of acidic fruits. * Apply cool compresses. * Wear loose, light clothing. * Avoid alcohol (it causes the surface blood vessels to dilate). * Minimize vigorous activity, which can release more irritants into the skin. * Use over-the-counter antihistamines to help relieve the itching * Cool the affected area with a fan, cold flannel, ice pack or soothing lotion. |
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