Differential Diagnosis > Other > Presentations > Pruritis

Pruritis

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These are people who itch but have no rash.  The most common cause of itch is dry skin (especially in the elderly), so address this first.

 

Instructions for dry/itchy skin:

change soap to unscented Dove
use Cetaphil cream moisturizer on damp skin after the shower
follow the "two-minute rule" = the moisturizer must be on the skin within two minutes of getting out of the shower or else the water evaporates and you lock in "nothing"

 

 

If itch persists you may consider other etiologies (mechanism is in parenthesis) :

chronic renal failure (increased serum histamine or kinin, and mast cell degranulation)
primary biliary cirrhosis (accumulation of bile salts)
*(characteristic lab findings = increased alk. phosphatase, (+) anti-mitochondrial antibodies)
other hepatic disorders: hepatitis, extrahepatic biliary obstruction
polycythemia vera [characteristically worse with hot baths]
thyrotoxicosis (kinins)
hypothyroid (secondary to dry skin)
malignancies:
Hodgkins = most common malignancy associated with itching
mycosis fungoides
confers a worse prognosis in both

 

 

Always think about and look for itchy dermatoses as well scabies, dermatitis herpetiformis, lichen planus:  

 

AND check for dermatographism if it is present, that is your answer and you can treat with Zyrtec 10 to 40mg/ day

 

lab tests

CBC infection, malignancy, hemolytic anemia, polycythemia vera, hypersensitivity (eosinophils)
LFTs primary biliary cirrhosis, other biliary disease
chem 7 uremia, diabetes
TSH thyroid disease
chest x-ray and lymph node exam Hodgkins disease

 

treatment:   UVB is very effective for most etiologies

pearl:  with end-stage renal disease - pruritis is more common with ACE inhibitors and less common with furosemide