Pruritus is itching of the skin. There are a vast number of dermatological causes of pruritus, which are usually visible on inspection. The following are causes of generalised pruritus in the absence of skin disease. A description of dermatological disorders is beyond the scope of this book. When approaching a patient with generalised pruritus, enquiries are made regarding the site and duration of symptoms. Occasionally the onset of pruritus will correlate with the initiation of drug treatment, allowing you to exclude the offending medication. It may also occur as a side-effect of alcohol or drug withdrawal. Pruritus after a hot bath classically occurs with polycythaemia. Iron deficiency, even in the absence of anaemia, can cause pruritus; therefore symptoms of blood loss in each system should be carefully elicited. Haemoptysis, chronic cough and weight loss in smokers may be due to underlying bronchial carcinoma, which is an important subgroup of internal malignancies that present with pruritus. The presence of localised lymphadenopathy, fever, night sweats and weight loss should lead to the consideration of Hodgkin’s disease. Patients with obstructive jaundice (p. 256) may present with pruritus (due to the accumulation of bile salts), even while the jaundice is not clinically apparent. With complete obstruction, patients may notice pale stools and dark urine. Lethargy, anorexia, nocturia, oliguria, polyuria, haematuria, frothy urine from proteinuria, skin fragility, oedema and bone pains are some of the multisystemic features suggestive of chronic renal disease. Interestingly, pruritus seldom occurs with acute renal failure. As pruritus may be due to thyroid disease, clinical assessment of the thyroid status is an important aspect of the history. Features of hyperthyroidism are tremor, heat intolerance, palpitations, increased appetite with weight loss, anxiety and diarrhoea. Features of hypothyroidism are cold intolerance, mental slowing, weight gain, constipation and menorrhagia.
Pruritus
History
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