For a patient with allergic rhinitis, what is a key lab finding that shows sensitivity to allergens?

In patients with allergic rhinitis, a key lab finding that indicates sensitivity to allergens is the presence of high levels of eosinophils. Eosinophils are a type of white blood cell that typically increase in response to allergies and parasitic infections. When a person is exposed to allergens, the immune system reacts by producing immunoglobulin E (IgE), leading to the activation and proliferation of eosinophils. These cells play a significant role in the inflammatory response associated with allergic conditions.

A high eosinophil count in the blood or tissue samples suggests that the body is responding to an allergic trigger. Therefore, this lab finding is critical for diagnosing allergic rhinitis and confirming the sensitivity of the patient to specific allergens.