14 Conditions That Can Impact Skin Testing
14.1 Setting the Stage for Success
Once the decision has been made to proceed with diagnostic testing, the next decision point is what type of allergy testing should be performed. While this book covers both skin testing and serum-specific immunoglobulin (IgE) testing (“blood” testing), only skin testing requires some candidate selection and preparation. Certain medical conditions or medications (with the exception of omalizumab) do not influence serum-specific IgE testing. In this chapter common conditions and medications that impact skin testing are discussed.
14.2 Medical Conditions
Dermatographism: The most common type of physical urticaria, resulting when a wheal and flare response appears when the skin is scratched or scraped. Due to the fact that this disorder makes skin reactivity unpredictable, patients with dermatographism should undergo serum-specific IgE testing.
Dermatitis (contact, eczema, etc.): Active skin inflammation of any kind is a contraindication to skin testing if it is occurring at the site(s) where testing will be performed. In addition, frequent use of topical steroid negatively affects the accuracy of skin testing, so testing should not be performed at sites where the patient uses topical steroids.
Asthma (poorly controlled, uncontrolled): While asthma itself is not a contraindication to skin testing, poorly controlled or uncontrolled asthma increases the risk of a serious adverse reaction during the procedure. Thus, before performing any skin testing, asthma patients should be assessed for level of control both subjectively, by history, and more objectively, by spirometry, peak flow meter, or fractional exhaled nitric oxide (FeNO) testing. If the patient is poorly controlled or uncontrolled, the decision should be made to either call the patient back once the asthma is controlled or to send he/she for another type of testing.
Pregnancy: With certain, select exceptions, skin testing should not be performed in a pregnant patient.
Other serious comorbid medical conditions: While these conditions may not directly impact the wheal and flare reaction, serious medical conditions such as a history of heart attack, stroke, peripheral vascular disease, etc., may impact the patient’s chance of surviving a serious adverse reaction. Any patient who has one or more serious medical condition(s) that would potentially reduce the chance of surviving a serious adverse reaction should be sent for specific IgE or other type of testing.
14.3 Medications
Certain medications affect skin testing: These consist H1-antihistamines, H2-antihistamines, certain tricyclic antidepressants, topical corticosteroids (chronic usage), and omalizumab.
Certain medications might affect skin testing: These consist benzodiazepines, topical calcineurin inhibitors, herbal remedies, and vitamin supplements.
Certain medications do not affect skin testing: These consist systemic oral corticosteroids, inhaled or intranasal steroids, leukotriene receptor antagonists, and selective serotonin reuptake inhibitors.
Other medications may affect skin testing, but haven’t been adequately studied.
This disclaimer can be included on the list of medications to stop and NOT to stop. A list should be given to the patient that shows not only what medications to stop and when to stop prior to testing, but what medications they should NOT stop.
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