Pruritus

Published on 23/05/2015 by admin

Last modified 22/04/2025

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Pruritus

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.

Causes

• Obstructive jaundice

• Chronic renal failure

Haematological Disease

• Iron deficiency

• Polycythaemia

Internal Malignancy

• Bronchial carcinoma

• Hodgkin’s disease

Endocrine Disease

• Hyperthyroidism

• Hypothyroidism

• Diabetes mellitus

Drugs

• Oral contraceptive pill (cholestasis)

• Opiates (histamine release)

• Alcohol and drug withdrawal

History

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.

Examination

Inspection

Wide, staring eyes with lid lag and tremor may be present with thyrotoxicosis. Pallor of the conjunctivae may be evident in severe anaemia, whereas, with polycythaemia, conjunctival insufflation and facial plethora occur. The sclera should also be examined for the presence of jaundice. Sallow skin with easy bruising and uraemic frost may be seen with chronic renal failure. Spoon-shaped nails of iron deficiency may be accompanied by angular cheilitis. Clubbing may be due to bronchial carcinoma.

General Examination

Asymmetrical, non-tender, localised lymphadenopathy in the absence of infection is suggestive of Hodgkin’s disease. The thyroid gland is palpated for abnormalities, such as enlargement, nodularity and asymmetry. A respiratory examination is performed; features of bronchial carcinoma include monophonic inspiratory wheeze (partial endoluminal bronchial obstruction), lobar collapse of the lung, pleural effusion and Horner’s syndrome with apical lung tumours. Chest wall tenderness may also occur as a result of tumour infiltration. Splenomegaly may occur with Hodgkin’s disease and polycythaemia rubra vera.