What does a skin prick test primarily measure?

A skin prick test primarily measures the presence of specific IgE antibodies in response to allergens. During the test, a small amount of allergen is introduced into the skin using a tiny prick. If an individual is sensitized to that allergen, the immune system produces specific IgE antibodies, which bind to mast cells in the skin. This binding leads to the release of histamine and other chemicals, resulting in a localized allergic reaction characterized by redness, swelling, and itching at the site of the prick.

This testing method is widely used because it helps identify immediate hypersensitivity reactions to various allergens, such as pollen, dust mites, pet dander, and certain foods. By quantifying the skin's reaction to different allergens, healthcare providers can make more informed diagnoses regarding allergies and their management.

Other options pertain to different medical measurements unrelated to the immune response to allergens, making them unsuitable in the context of a skin prick test.