In this test, the person is immersed in water at 43 °C (109.4 °F). Someone with EU will not develop hives, while a person with cholinergic urticaria will develop the characteristic small hives, especially on the neck and chest.The immediate symptoms of this type are treated with antihistamines, epinephrine and airway support. Taking antihistamines prior to exercise may be effective. Ketotifen is acknowledged to stabilise mast cells and prevent histamine release, and has been effective in treating this hives disorder. Avoiding exercise or foods that cause the mentioned symptoms is very important. In particular circumstances, tolerance can be brought on by regular exercise, but this must be under medical supervision. Pathophysiology
The skin lesions of urticarial disease are caused by an inflammatory reaction in the skin, causing leakage of capillaries in the dermis, and resulting in an edema which persists until the interstitial fluid is absorbed into the surrounding cells.Hives are caused by the release of histamine and other mediators of inflammation (cytokines) from cells in the skin. This process can be the result of an allergic or nonallergic reaction, differing in the eliciting mechanism of histamine release. Allergic hives
Histamine and other proinflammatory substances are released from mast cells in the skin and tissues in response to the binding of allergen-bound IgE antibodies to high-affinity cell surface receptors. Basophils and other inflammatory cells are also seen to release histamine and other mediators, and are thought to play an important role, especially in chronic urticarial diseases.
Chloroquine retinopathy is a form of toxic retinopathy (damage of the retina) caused by the drugs chloroquine or hydroxychloroquine, which are sometimes used in the treatment of autoimmune disorders such as rheumatoid arthritis and systemic lupus erythematosus. This eye toxicity limits long-term use of the drugs. Presentation
The risk of toxicity is low for individuals without complicating conditions during the first five years of treatment using less than 6.5 mg/kg/day of hydroxychloroquine or 3 mg/kg/day of chloroquine, and/or cumulative doses of less than 1000 gram and 460 gram (total dose), respectively. Some physicians suggest that lean body weight is more accurate when calculating daily dosage.Most patients are routinely given 400 mg of hydroxychloroquine daily (or 250 mg chloroquine). This dose is considered acceptable. Early stage
The earliest signs of toxicity include bilateral paracentral visual field changes (best detected with a red test object) and a subtle granular depigmentation of the paracentral RPE. Advanced stage
With continued drug exposure, there is progressive development of a bilateral atrophic bulls-eye maculopathy and paracentral scotomata, which may in severe cases ultimately spread over the entire fundus, causing widespread retinal atrophy and visual loss. Pathophysiology
Both agents bind to melanin pigment in the RPE, and this may serve to concentrate the drugs or to prolong their adverse effects. Diagnosis
Patients and their primary care physicians must be made fully aware of the ophthalmic risks and the need for regular screening examinations to detect retinal toxicity at an early stage.