July 27, 2017
Generalised Itching Minimize

Generalised itching

Patients with scratch marks but without a recognisable dermatosis may have an underlying metabolic abnormality. There are a large number of causes and this framework for investigation will depend on the history and clinical signs.

Dermatological disorders

Skin disorders are the most frequent cause of itching and can usually be diagnosed by their appearance. However, it is important to recognise that scratch marks and secondary dermatoses can be due to non-dermatological conditions.

Metabolic disorders

  • Obstructive biliary disease eg primary biliary cirrhosis, pregnancy associated cholestasis
  • Renal failure
  • Haematological disorders eg polycythaemia rubra vera, iron deficiency, mastocytosis
  • Thyroid disease
  • CNS disorders 
  • Lymphoma

Lymphoma/malignancy

The best investigation for malignancy causing pruritus is a thorough clinical examination.

Drugs

associated with cholestasis

others

anabolic steroids

aspirin

chlopromazine

chloroquine

erythromycin

canthaxanthin

phenothiazines

carbamazepine

tolbutamide

cromoglycate

 

dexamethasone & hydrocortisone

 

gold salts

 

invermectin

 

isoniazid

 

opiates

 

quinidine

 

streptomycin

Pregnancy

Intrahepatic cholestasis of pregnancy produces generalised itching which may or may not eventually be accompanied by jaundice. It may begin as early as the twentieth week of pregnancy and remits promptly after delivery.  LFTs reveal increased bilirubin and alkaline phosphatase with normal transaminases.

AIDS

Patients with AIDS may have primary pruritus but it is usually due to an inflammatory or infective dermatosis.

Reference

  • Gelman GR, Rumack BH (eds). Drugdex (R) Information System. Denver: Micromedex Inc (edition expires 31 Dec 1998).
  

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