Andrea Nguyen, DMSc, MPAS, PA-C

In this episode titled “Distinguishing CSU From Chronic Inducible Urticaria Subtypes,” the panel looks at how CSU differs from chronic inducible urticaria (CIndU) and its subtypes. The panelist explains that inducible urticarias have an identifiable physical trigger, the most common being dermatographism, in which scratching, tight clothing, or waistbands provoke hives at the site of pressure. Cold-induced urticaria is another recognizable subtype, often described by patients as hives that appear after re-warming following cold exposure, such as a child breaking out after a chilly soccer practice.

Distinguishing CSU From Chronic Inducible Urticaria Subtypes

The panelist stresses that many CSU patients also report a component of dermatographism or other inducible triggers, but this does not change the underlying diagnosis: a patient only qualifies as having a true inducible urticaria if hives occur exclusively with the trigger and never spontaneously. Misclassifying these patients as having an inducible urticaria rather than CSU is a meaningful error, since it unnecessarily limits available treatment options. Published data suggest 10% to 30% of CSU patients also experience concomitant inducible urticaria, meaning clinicians must carefully tease out whether hives ever occur without a trigger before assigning a diagnosis.

The panel agrees that accurately identifying the spontaneous component of a patient’s urticaria, rather than focusing solely on apparent triggers, is essential for ensuring patients are not steered away from the more effective advanced therapies available for CSU. This distinction carries real clinical stakes, since treatment options for a true inducible urticaria remain far more limited than the advanced therapy classes now approved specifically for CSU. Taking the time to clarify whether hives ever truly occur in the absence of a trigger, rather than assuming a label based on the most obvious provoking factor, ultimately determines which treatments a patient can access. In the next episode, “A Practical Diagnostic Workup for CSU,” the panel shares a bedside approach to confirming CSU, differentiating it from urticarial vasculitis, and explaining why extensive lab and allergy testing usually adds little value.

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Welcome back to another HCPLive Peers & Perspectives series. In this episode titled “Diagnosing the Hallmark Signs and Symptoms of CSU,” moderator Andrea Nguyen, DMSc, MPAS, PA-C, discusses chronic spontaneous urticaria (CSU) with Matthew Zirwas, MD. The episode opens with the moderator asking the panelist to describe the hallmark signs of CSU and the patient population most affected. The panelist explains that CSU is defined by spontaneously appearing hives that present as raised, red wheals surrounded by a blanched halo, can occur anywhere on the body, and typically resolve and recur unpredictably. He notes that roughly one-third of patients also develop angioedema, deep tissue swelling that commonly affects the lips, face, or hands. While CSU can occur at any age, including in children and older adults, onset is most common among women in their 20s and 30s.

Diagnosing the Hallmark Signs and Symptoms of CSU

The panelist highlights a strong association between CSU and autoimmune thyroid disease, recommending that patients have anti-thyroid peroxidase antibodies checked and, regardless of the result, undergo annual TSH monitoring for life, since elevated thyroid risk often develops over time even when initial testing is normal. He frames CSU for patients as an autoimmune condition that raises susceptibility to other autoimmune diseases, helping set expectations for long-term monitoring.

The conversation also touches on the well-documented female predominance of CSU, cited at roughly a 2-to-1 ratio in published literature, though clinical impression in practice can skew even more heavily toward women, possibly reflecting differences in care-seeking behavior between sexes. Population-based estimates, including a recent claims-data analysis, place CSU prevalence at approximately 0.78%, translating to several million affected Americans. The panel underscores that despite being common and burdensome, CSU is frequently underrecognized in clinical practice, setting the stage for a deeper discussion of diagnostic nuances ahead. In the next episode, “Distinguishing CSU From Chronic Inducible Urticaria Subtypes,” the panel explains how to tell true inducible urticarias apart from CSU with an inducible component, and why getting that distinction right protects patient access to effective therapy.

Andrea Nguyen, DMSc, MPAS, PA-C

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