Pruritis/Pruritic Conditions

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Pruritis/Pruritic Conditions

Pruritis (itching) is an unpleasant sensation in which the patients attempts to relieve by scratching or rubbing – it is a common symptom and not a disease entity. There is a special neural pathway for itching.

Many conditions cause pruritic/itchy symptoms – eg scabies, insect bites, atopic dermatitis, urticaria, lichen planus, dermatitis herpetiformis, thyroid disease, severe renal failure, liver disease; polycythemia vera (in up to a third);
Dry skin in the elderly can cause a generalised pruritis.

Pathophysiology, the pruritis is activated at the dermal-epidermal junction by activation of free nerve ending by local mediators (eg histamine); sensation is carried by unmyelinated C fibres from the subepidermal region via the lateral spinothalamic tract to the thalamus and sensory cortex

Treatment:
• identify and correct cause
• itch/scratch cycle needs to be disrupted
• emollients, cooling of skin,
• oral agents – tricyclic antidepressants (potent H1 antagonists), doxepin, antihistamines

Dermatitis herpetiformis:
Highly pruritic condition characterised by multiple small vesicles.
IgA and complement are deposited beneath basement membrane
Associated with gluten sensitivity

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