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SOURCE

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Source: May JR. Allergic rhinitis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=134128639. Accessed March 28, 2017.

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CONDITION/DISORDER SYNONYMS

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  • Hay fever.

  • Pollinosis.

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DEFINITION

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  • Inflammation of nasal passages caused by allergic reaction to airborne substances.

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ETIOLOGY

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  • Seasonal: Occurs in response to specific allergens (pollen from trees, grasses, and weeds) present at predictable times of year (spring and/or fall blooming seasons).

  • Perennial: Occurs year-round in response to nonseasonal allergens (eg, dust mites, animal dander, and molds).

  • Many patients have both types, with symptoms year-round and seasonal exacerbations.

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PATHOPHYSIOLOGY

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  • Airborne allergens inhaled into nose processed by lymphocytes, producing immunoglobulin E (IgE).

    • On nasal reexposure, IgE bound to mast cells interacts with airborne allergens, triggering release of inflammatory mediators.

  • Within seconds to minutes, rapid release of mediators (histamine, leukotrienes, prostaglandin, tryptase, kinins) causes:

    • Vasodilation.

    • Increased vascular permeability.

    • Nasal secretions.

  • Histamine produces:

    • Rhinorrhea.

    • Itching.

    • Sneezing.

    • Nasal obstruction.

  • Late-phase reaction 4–8 hours after initial exposure may cause chronic symptoms, including nasal congestion.

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EPIDEMIOLOGY

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  • One of the most common disease affecting adults and the most common chronic disease in children in the United States.

  • Prevalence of seasonal rhinitis between 1% and 40%; perennial rhinitis prevalence ranges from 1% to 13%.

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PREVENTION AND SCREENING

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  • Allergen avoidance important to prevent episodes but often difficult to accomplish.

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RISK FACTORS

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  • Genetics.

  • Allergen exposure.

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CLINICAL PRESENTATION

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SIGNS AND SYMPTOMS
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  • Clear rhinorrhea; sneezing; nasal congestion; postnasal drip (occasionally with cough or hoarseness); allergic conjunctivitis; and pruritic eyes, ears, or nose.

  • May be loss of smell or taste, with sinusitis or polyps underlying cause in many cases.

  • Untreated rhinitis may lead to:

    • Insomnia.

    • Malaise.

    • Fatigue.

    • Poor work or school performance.

  • Complications include recurrent and chronic sinusitis and epistaxis.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Medical history for:

    • Description of symptoms.

    • Environmental factors and exposures.

    • Results of previous therapy.

    • Use of medications.

    • Previous nasal injury or surgery.

    • Family history.

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LABORATORY TESTS
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  • Radioallergosorbent test (RAST) to detect IgE antibodies in blood specific for given antigen.

  • Peripheral blood eosinophil count may be elevated but is nonspecific finding.

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DIAGNOSTIC PROCEDURES
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  • Percutaneous allergy testing can help determine whether rhinitis caused by immune response to allergens.

  • Microscopic examination of nasal scrapings typically reveals numerous eosinophils.

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DIFFERENTIAL DIAGNOSIS
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  • Viral rhinitis (common cold)

  • Viral conjunctivitis.

  • Vasomotor rhinitis.

  • Acute or chronic sinusitis

  • Rhinitis medicamentosa.

  • Nasal polyposis.

  • Foreign body.

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DESIRED ...

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