Investigations

First line investigation in patient with pruritus with no obvious cause:

• 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) (1,2), crawling (3)
  • location - scapula/subscapula, 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 (1)
• laboratory investigations
  • urine - dipstick for glucose
  • blood tests - FBC, ESR, U+Es, Ca, LFTs, Fe, TFTs, immunoglobulins (1)
• other investigations
  • consider chest X-ray
  • abdominal ultrasound (lymphoma)
  • skin biopsy (1)

Patients who complain of itch who have a definite skin lesion do not usually need further investigation (3). Exceptions include the use of patch testing in suspected allergies and a skin biopsy in the case of suspected dermatitis herpetiformis.

Reference:

• (1) Twycross R et al. Itch: scratching more than the surface. Q J Med 2003; 96: 7-26
• (2) Hiramanek N. Itch: a symptom of occult disease. Aust Fam Physician. 2004;33(7):495-9
• (3) Rishe E, Azarm A, Bergasa NV. Itch in primary biliary cirrhosis: a patients' perspective. Acta Derm Venereol. 2008;88(1):34-7
• (3) Update (20/8/97), 169-70.