Types
Localized pruritis:
- Primary skin lesion is present. If primary skin lesion is absent it can be neuropathic or psychogenic pruritis
- In the scalp, pruritis may be due to psoriasis or ongoing folliculitis
- In the inguinal or anal region- due to prutitis ani, pruritis vulvae, pruritis scroti, veneral diseases, scabies, pediculosis
- In the hands and feet due to psoriasis, contact dermatitis
- In the mid back due to nostalgia paresthetia, macular amyloidosis
- In the lower limbs in older patients due to asteatosis
Systemic disorders :
- Endocrine – DM, hyperthyroidism, hypoparathyroidism, myxoedema
- Hepatic – cholestasis, Hepatitis B and C virus infection, cholestasis of pregnancy
- Renal – chronic renal insufficiency
- Blood disease (hematological) – iron deficiency anaemia, leukemia, multiple myeloma, mycosis fungoides, mast cell disorders
- Intestinal parasites – infestation with hookworm, round worm, pin worm
- Collagen vascular disorders – SLE
- Neurological – Multiple sclerosis, brain tumour
- Pregnancy
Psychogenic pruritis – psychosomatic disorders resulting in itch commonly occur in middle aged or older individuals
Iatrogenic pruritis – induced by opium alkaloids, CNS stimulants, antidepressants, belladonna alkaloids