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Hives, also known as urticaria, is a kind of skin rash with red and/or flesh-colored, raised, itchy bumps. [1] Hives may burn or sting. [2] The patches of rash may appear on different body parts, [2] with variable duration from minutes to days, and do not leave any long-lasting skin change. [2]
Symptoms are thought to be the result of histamine being released by mast cells on the surface of the skin. Despite the lack of antigens , histamine causes the skin to swell in affected areas. If the membrane that surrounds the mast cells is too weak, it will easily and rapidly break down under physical pressure, which then causes an allergic ...
Several theories have been put forth, however the pathophysiology of pressure urticaria is unknown. [3] Although there isn't an obvious early cutaneous reaction, the time of the reaction following the application of pressure to the skin, the shape of the lesions, and the infiltrating cells observed on histopathologic examination are indicative of a late-phase reaction. [5]
Other symptoms accompanying a hypertensive crisis may include visual deterioration due to retinopathy, breathlessness due to heart failure, or a general feeling of malaise due to kidney failure. [3] Most people with a hypertensive crisis are known to have elevated blood pressure, but additional triggers may have led to a sudden rise. [4]
It is also important to rule out systemic diseases that can cause hives, such as vasculitis (urticarial vasculitis), Schnitzler's syndrome, Gleich's syndrome, or thyroid disease. [32] The specific symptoms, triggers, and results of skin and blood tests can help differentiate autoimmune urticaria from these other conditions.
Physical urticaria is a distinct subgroup of urticaria (hives) that are induced by an exogenous physical stimulus rather than occurring spontaneously. [1] There are seven subcategories that are recognized as independent diseases. [2] [3] Physical urticaria is known to be painful, itchy and physically unappealing; it can recur for months to ...
In hypertensive encephalopathy, generally the blood pressure is greater than 200/130 mmHg. [1] Occasionally it can occur at a BP as low as 160/100 mmHg. [ 4 ] This can occur in kidney failure , those who rapidly stop blood pressure medication , pheochromocytoma , and people on a monoamine oxidase inhibitor (MAOI) who eat foods with tyramine. [ 2 ]
A hypertensive emergency is not based solely on an absolute level of blood pressure, but also on a patient's baseline blood pressure before the hypertensive crisis occurs. Individuals with a history of chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension , including fatigue ...