Urticaria & Itch Flashcards
definition of urticaria
a transient (<24h) eruption of erythematous and oedematous swellings of the dermis, usually ass. with itching
other names for urticaria
“nettle rash”
hives
wheals
acute urticaria duration
<6 weeks
chronic urticaria duration
> 6 weeks
definition of angio-oedema
transient (24-48h at most) swellings in the deeper dermal, subcutaneous and submucosal tissues
mediators that are released by mast cell degranulation
proteases e.g. tryptase histamine heparin Cytokines - e.g. IL-3 Prostaglandins Leukotrienes e.g. CD4
is allergy a common cause of chronic urticaria?
NO - nearly never.
almost always acute urticaria
drugs causing urticaria
mostly salicylates e.g. aspirin
most common autoimmune cause of uritcaria
SLE
endocrine disease ass. with urticaria
Thyroid disease
Infective causes of urticaria
dental infections
candida
causes of angioedema
All the causes of urticaria
C1 esterase inhibitor deficiency (inherited or acquired)
ACEi
suppressive Tx of urticaria
- Txs that block the effect of mediators released from mast cells
- H1 and H2 antagonist antihistamines
- leukotriene antagonists
- serotonin antagonists - Txs that make mast cells less likely to degranulate
- UV phototherapies
- Ketotifen
4 general categories of causes of itch
Pruritoceptive
Neuropathic
Neurogenic
Psychogenic
What is a pruritoceptive itch
something - usually inflammation or dryness - in skin that triggers itch
