From the Guidelines
The best approach for evaluating worsening idiopathic pruritus begins with a thorough history and physical examination to identify potential underlying causes, as recommended by the British Association of Dermatologists' guidelines 1.
Initial Evaluation
The evaluation should include:
- A detailed history to identify potential triggers such as new medications, soaps, detergents, or environmental changes
- A physical examination to rule out visible lesions or other skin conditions
- Laboratory testing, including:
- Complete blood count to rule out blood disorders
- Comprehensive metabolic panel to exclude systemic causes like kidney disease or liver dysfunction
- Thyroid function tests to rule out thyroid disorders
- Age-appropriate cancer screenings to exclude malignancy
Investigation of Underlying Causes
The British Association of Dermatologists' guidelines recommend the following investigations for generalized pruritus without an underlying dermatosis 1:
- Full blood count and ferritin levels to check for iron deficiency
- Liver function tests to rule out liver disease
- Urea and electrolytes to rule out uraemia
- Consideration of haematological involvement, including initial investigations such as full blood count, blood film, lactate dehydrogenase, and erythrocyte sedimentation rate
Symptom Management
For symptom management while investigating causes, first-line treatments include:
- Regular use of emollients
- Topical corticosteroids like triamcinolone 0.1% cream twice daily for up to two weeks on affected areas
- Oral antihistamines such as cetirizine 10mg daily or hydroxyzine 25mg at bedtime, as recommended by the ESMO clinical practice guidelines 1
Referral to Specialist Care
For persistent symptoms, consider referral to dermatology for advanced treatments like phototherapy, systemic immunomodulators, or neuromodulating agents such as gabapentin or pregabalin, as recommended by the British Association of Dermatologists' guidelines 1.
From the FDA Drug Label
For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested. Useful in the management of pruritus due to allergic conditions such as chronic urticaria and atopic and contact dermatoses and in histamine-mediated pruritus
The best approach for evaluating worsening idiopathic pruritus is not directly addressed in the provided drug labels.
- Key points to consider when evaluating worsening idiopathic pruritus include identifying potential underlying causes and assessing the patient's response to therapy. However, the FDA drug label does not provide information on the evaluation of worsening idiopathic pruritus. 2 2
From the Research
Evaluation Approach for Worsening Idiopathic Pruritus
- A thorough history, review of symptoms, and laboratory evaluation should be performed, particularly for people with chronic pruritus lasting less than 1 year 3.
- The initial evaluation should include a complete blood count, with differential, hepatic, renal, and thyroid function testing along with diabetes screening 4, 5.
- Clinicians should consider the following tests: complete blood cell count, complete metabolic panel, and thyroid function testing to evaluate for hematologic malignancy, liver disease, kidney disease, or thyroid disease 3.
- Further testing should be guided by history and physical examination findings, and there should be a heightened concern for underlying malignancy in individuals older than 60 years of age who have a history of liver disease and diffuse itch less than 12 months of duration 5.
- For individuals with chronic pruritus of unknown origin, increased blood eosinophils may serve as a biomarker of T helper cell type 2 polarization and response to immunomodulator therapies 5.
Diagnostic Considerations
- Chronic pruritus can be categorized into inflammatory, neuropathic, or a combined etiology, and the evaluation should consider these different etiologies 3, 6.
- Localized cutaneous pruritus is indicative of a neuropathic cause, whereas generalized cutaneous pruritus suggests underlying systemic disease(s), drug-induced itch, psychogenic itch, or chronic pruritus of unknown origin (CPUO) 6.
- Systemic diseases associated with cutaneous pruritus include disorders of iron metabolism, chronic kidney disease, chronic liver disease, endocrine/metabolic diseases, hematological disorders, and malignant solid tumors 6.
Assessment Tools
- Pruritus intensity scales, instruments for assessment of scratch lesions, chronic pruritus course, quality of life, and patient benefits are recommended for use in clinical trials to assess pruritus 7.
- A set of measures including pruritus intensity scales and quality of life instruments can be used to evaluate the severity of pruritus and the effectiveness of treatments 7.