Elevated eosinophils play a key role in HES


Each patient with hypereosinophilic syndrome (HES) may present differently, and since HES is a rare disease (estimated prevalence of 5000 in the US*), it may be more difficult to diagnose.1,2 A thorough workup is essential for evaluating a patient who is presenting with hypereosinophilia.1 Below are some factors to consider when identifying patients with HES.

Defining hypereosinophilic syndrome3

Peripheral blood hypereosinophilia (>1500 cells/μL) on 2 exams (interval ≥1 month)


Eosinophil-mediated organ dysfunction and/or damage


Exclusion of other disorders as a major reason for organ damage

Clinical manifestations vary depending on organ involvement1,4

All HES patients are different. Patients may present with single- or multiple-organ involvement. Organs and organ systems that may be impacted by HES include:

Diagram depicting organs and organ systems that may be impacted by hypereosinophilic syndrome (HES)
Diagram depicting organs and organ systems that may be impacted by hypereosinophilic syndrome (HES)


*Estimate based on the National Hospital Discharge Survey of ~6000 discharges with at least 1 discharge diagnosis with the ICD code for eosinophilia; ~2000 cases were compatible with HES. The ratio of outpatients to inpatients (2.5:1) from a US claims database was applied to determine the final estimate.2

Diagnosis can be made immediately to avoid delay in therapy in the case of life-threatening organ damage.3

Differentiating HES from EGPA

Characteristics and clinical manifestations of HES overlap with those of eosinophilic granulomatosis with polyangiitis (EGPA). See below for similarities and differences between these two conditions.5

  Features of HES include:   Features of EGPA include:
  Peripheral blood hypereosinophilia (>1500 cells/μL on ≥2 occasions at least 1 month apart)3   Eosinophilia >10%6
  Vasculitic complications are rare6   Eosinophil-rich, necrotizing granulomatous vasculitis affecting small-to-medium sized vessels7
  Pulmonary manifestations occur; presence of asthma and nasal polyps is rare6   Frequent asthma and nasal polyps6
  ANCA-negative6   ~40% of patients have ANCA antibodies8,9
  Patients may experience systemic manifestations   Patients may experience systemic manifestations
Eosinophil reduction image

Eosinophil reduction and mechanism of action (MOA)

See the results of NUCALA on eosinophil reduction

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Flare reduction

Proportion of patients with flares and time to first flare