Innovative Management of Pruritus

Pruritus remains a significant problem facing dermatologists and can be associated with various dermatoses and systemic derangements. At times, one can treat the underlying cutaneous or systemic process to alleviate itch. However, it is frequently challenging to identify the cause of a patient’s itch and, in this situation, even more difficult to manage the symptom effectively. In this article, the authors discuss the approach to a patient with generalized pruritus without clinically obvious dermatoses. They also addresses mechanisms and management modalities of itch in common systemic diseases, including cholestasis, uremia, and neuropathic dysfunction.

Itch is defined as the unpleasant sensation of the skin resulting in a desire to scratch and is often classified as acute and chronic. Pruritus can be an extremely distressing symptom that dramatically affects the quality of life. Other classifications of itch are based on where the sensation is located (generalized versus localized or shifting): specifically, as pruritus on diseased or inflamed skin; as pruritus on nondiseased or noninflamed skin; or as pruritus presenting with severe, chronic secondary lesions related to scratching. The incidence of pruritus in the general population is poorly documented. However, chronic renal failure and liver failure are associated with pruritus in up to 75% of patients. In this article the authors focus on pruritus affecting noninflamed or nondiseased skin. Processes in this category include cholestasis, uremia, neuropathic derangement, thyroid disorders, iron deficiency, polycythemia vera, essential thrombocytosis, malignancy, human immunodeficiency virus (HIV)/AIDS, and medication-induced itch. In many of these conditions, the pruritus is best resolved by treatment of the underlying condition; however, this treatment may not always be possible or sufficient. Thus, the authors review current mechanisms and new innovative therapies to treat intractable pruritus of selected systemic diseases.

Pruritus workup

Itch can be caused by inflammatory skin diseases, exogenous trigger factors (eg, mites, virus), endogenous trigger factors (eg, systemic drugs), or systemic diseases (eg, chronic renal insufficiency). To properly treat a patient with pruritus, an effort must be made to determine the precise cause of the itch. The authors recommend that when a patient presents to the dermatologist with a chronic itch (lasting longer than 6 weeks), a detailed history and full skin examination should be performed. Of note, the skin of a patient with pruritus may seem normal. It may alternatively reveal an underlying disease, show specific features of a dermatosis (eg, hives in urticaria), or may only show unspecific scratching “artifacts” (ie, pruritus on primary nondiseased skin). If a primary dermatologic or systemic process is identified, then appropriate disease-specific workup and treatment is indicated. If the patient has pruritus without inflamed or diseased skin, the authors suggest that, in addition to the full skin examination and detailed medical and medication history, a set of general laboratory studies be obtained, including a complete blood count with differential, sedimentation rate, levels of creatinine and glucose, liver function tests (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin), thyroid function tests (thyroid stimulating hormone, free T4); iron studies (transferrin saturation, ferritin, iron), rapid plasma reagin for syphilis, HIV antibody test, and a chest radiograph. More specialized tests may be indicated based on medical history (eg, antinuclear antibody, hepatitis serology, antimitochondrial antibody, antigliadin antibody, antitransglutaminase antibody, parathyroid hormone, calcium, phosphate, specific immunoglobulin (Ig) E, functional anti-IgE Fc receptor antibody, serum tryptase, serotonin and its metabolites, stool for ova and parasites or stool occult blood examination). Sometimes, allergy testing (prick or patch testing), histologic examination of affected skin, and direct immunofluorescence and internal evaluations such as ultrasound or radiologic imaging (magnetic resonance imaging [MRI], computed tomography [CT]) may also be beneficial. An age-appropriate malignancy workup is warranted if these initial studies are unremarkable or if the history and review of systems suggest a possible malignancy. Thus, the approach to identify the origin of pruritus may be complex and multidisciplinary.

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