Overview
Hypereosinophilic syndrome (HES) is a rare condition caused by an overload of white blood cells called eosinophils. Eosinophils protect your body from parasitic infections and respond to allergens. Normally, eosinophils account for 5% to 7% of your white blood cells, or about 100 to 500 eosinophils per microliter of blood. When you have certain conditions, such as allergies, your eosinophils multiply to cause a condition called eosinophilia.
Hypereosinophilic syndrome happens when eosinophilia accelerates, speeding up eosinophil production and increasing the number of eosinophils. This eosinophil overload can damage your organs, including your heart, lungs, skin and nervous system. Left untreated, hypereosinophilic syndrome can be life-threatening. Fortunately, prompt diagnosis and treatment mean more than 80% of those diagnosed with hypereosinophilic syndrome are alive five years after diagnosis.
Who’s affected by hypereosinophilic syndrome?
HES is a rare condition, and healthcare providers aren’t sure how many people have HES. Anyone can develop hypereosinophilic syndrome, but it’s most often seen in people ages 20 to 50.
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