urticaria Flashcards
what is urticaria
hives
what is the presentation of urticaria
pruritic, circumscribed, erythematous raised plaques
blanch completely when pressure is applied
may have central pallor
occasionally accompanied by angiodema
when are sx of urticaria more severe
at night
what shape are hives
round, oval or irregular
what causes acute urticaria
sometimes presumptive trigger
what causes chronic urticaria
often idiopathic
what age group commonly gets urticaria
wide age distribution
what part of the body is affected most by urticaria
any body part can be affected
waistbands + axilla are more dramatic in presentation
what is the role of angioedema in urticaria
sometimes present
indicates involvement of deeper SQ tissue (face, lips, extremities +/- genitals)
what percent of the US has had acute urticaria? chronic?
acute- 20%
chronic- 1%
when do lesions of acute urticaria resolve
usually within 24hrs, self-limiting
present for <6wks
which gender experiences acute urticaria more frequently
neither
men = women
how often does chronic urticaria occur
most days for >6wks
in which decades of life does chronic urticaria usually occur
4th + 5th decades
which gender experiences chronic urticaria more frequently
women
etiology of urticaria
no specific etiology
infections- viral, bacterial, parasitic
allergic- meds, stings, latex, foods, environment (heat, cold, pressure), transfusion rxns
systemic disorders- urticarial vasculitis (non-blanching lesions), cutaneous small vessel vasculitis, autoimmune (SLE, sjogrens, celiac dz, autoimmune thyroid dz)
diagnosis of urticaria
not indicated in new onset cases which do not suggest underlying disorder
consider to r/o underlying illness if hx is suggestive (CBC w diff, ESR/CRP, UA, LFTs)
if allergic- serum test for IgE antibodies, refer to allergist/immunologist
treatment goals of acute-new onset urticaria
short-term relief of pruritis + angioedema if present
treat anaphylaxis/emergent cases prn
2/3 will resolve spontaneously (often w.o scarring)
medications for acute-new onset urticaria
H1 antihistamines:
- -1st gen- benadryl (diphenhydramine)
- -2nd gen- zyrtec (cetirizine), claritin (loratidine)
H2 blockers
- -zantac (ranitidine)
- -pepcid (Famotidine)
steroids- brief course to control persistent + severe sx, do not inhibit mast cells but suppress contributing inflam mechanisms
counseling for chronic urticaria
rarely permanent- 50% resolve in 1yr
rarely puts pts in any acute risk
sx can be managed
avoid triggers
medications for chronic urticaria
steroids- rescue therapy to attain control of severe sx
H1 antihistamines:
- -1st gen- benadryl (diphenhydramine)
- -2nd gen- zyrtec (cetirizine), claritin (loratidine)
H2 blockers:
- -zantac (ranitidine)
- -pepcid (famotidine)
step-wise approach to treating chronic urticaria w meds
1) 2nd gen H1 at standard dose
2) advance dose of 2nd gen H1
3) add H2 blocker
4) add leukotriene inhibitor
5) add 1st gen H1 at bedtime
6) advance dose of 1st gen H1 gradually
**When sx are controlled- continue for min 2-3mo before beginning to taper
