Clinical Classification For Urticaria Flashcards
What is acute urticaria?
Last less than 6 weeks
Usually non-specific trigger commonly viral of nature through non-immune mechanisms
What is chronic urticaria?
Persistent for longer than 6 weeks and usually a physical urticaria or a chronic autoimmune urticaria
What is an episodic urticaria?
Last short periods intermittently but recurring over months or years.
Caused by recurrent episodic exposure to an allergic trigger.
What causes urticaria
Mast cell degranulation
How are mast cells degranulated
Immune system- allergic urticaria
Direct release- non-allergic urticaria
How is allergic urticaria divided?
IgE-mediated
Non-IgE-mediated
What composes the IgE-mediated urticaria
Local
Generalised- Acute IgE mediated
What makes up the non-IgE mediated urticaria (5)
Direct mast cell destabilisation Drugs Viral infection Exogenous histamine Physical stimuli
What causes direct mast cell destabilisation
Strawberries
Shellfish
What drugs cause non-IgE mediated allergic reaction?
Opiate
Radiocontrast
Vancomycin - red men syndrome
What is the most common cause for acute urticaria
Viral infection
They last longer than other causes of acute urticaria
What is possible source from exogenous histamine
Scombroid fish poisoning as the dark meat contain histadine which than becomes histamine when spoiled
How does Scombroid fish poisoning present
Flushing Urticaria Vomiting Diarrhoea This a toxic adverse reaction
Name the different physical urticaria (7)
Dermatographism Cold urticaria Cholinergic urticaria Delayed pressure urticaria Solar urticaria Aquagenic urticaria Vibration urticaria
What is the most common physical urticaria?
Dermatographism
What causes Dermatographism
Stroking or scratching the skin with light- moderate touch/pressure
How is Dermatographism diagnosed
By eliciting and demonstrating it
What causes cold urticaria
Cold weather
Handling cold objects
Bathing in cold water
What are the types of cold urticaria
Localised
Systemic which is dangerous as it can cause severe symptoms such as hypotension and collapse as well as drowning when immersed in cold water
Cold-induced Dermatographism
How is cold urticaria diagnosed
Ice tube in thin plastic is placed on site for 5-10 minutes if there is urticaria when rewarming than you have cold urticaria
What is cholinergic urticaria
Generalised heat-induced urticaria
What causes cholinergic urticaria
Exercise Sweating Hot showers Emotional stress Fever
Why is it named cholinergic not heat-induced urticaria
Because the sweat glands enervated with cholinergic nerve fibres are responsible for this
How is cholinergic urticaria diagnosed
By sweating exercise (and 15minutes after sweating)
Passively heating body temperature
