Investigations

First line investigation in patient with pruritus with no obvious cause: (1)

• detailed history and examination -
  • timing of itch - day or night, intermittent or continuous
  • nature – burning (in Hodgkin disease), pricking (occurs most frequently after hot baths in polycythaemia rubra vera patients), crawling
  • location - scapula/subscapular area, palms of hand and soles of feet (in cholestasis)
  • provoking factors - activity/exercise, cold, water, sunlight
  • medications – opioids
  • physical examination – dry skin, scabies, mental status
• laboratory investigations
  • urine - dipstick for glucose
  • blood tests - FBC, ESR, U+Es, Ca, LFTs, Fe, TFTs, immunoglobulins
• other investigations
  • consider chest X-ray
  • abdominal ultrasound (lymphoma)
  • skin biopsy

Patients who complain of itch who have a definite skin lesion do not usually need further investigation. Exceptions include the use of patch testing in suspected allergies and a skin biopsy in the case of suspected dermatitis herpetiformis.

Reference:

1. Ständer S, Zeidler C, Augustin M, et al. S2k guideline: diagnosis and treatment of chronic pruritus. J Dtsch Dermatol Ges. 2022 Oct;20(10):1387-402.