hudprikktest

The hudprikktest, known in English as the skin prick test (SPT), is an in vivo diagnostic method used to identify IgE-mediated sensitization to specific allergens. It involves applying small amounts of allergen extracts to the surface of the skin, usually on the forearm or back, followed by a shallow puncture with a sterile lancet to introduce the allergen into the epidermis. A positive and a negative control are typically included, with histamine serving as the positive control and saline as the negative control. Results are read after about 15 to 20 minutes; a wheal (raised, pale area) surrounded by a flare indicates sensitization. The size of the wheal is measured in millimeters and is interpreted in the context of controls and clinical history, with thresholds varying by age and testing protocol.

Indications include suspected IgE-mediated allergies to foods, inhalant allergens, or venom, and the test helps to guide avoidance strategies and the consideration of immunotherapy. It is not a test of clinical allergy by itself, and a positive result does not necessarily mean that exposure will cause symptoms. Conversely, a negative test does not completely exclude allergy, especially if the history is strong.

Contraindications include extensive dermatitis at the test sites and conditions that may confound interpretation. Medications such as many antihistamines can suppress reactions and may need to be withheld before testing. Risks are generally low but systemic reactions, while rare, can occur. Alternatives include serum-specific IgE testing (blood tests) and, when needed to establish causality for foods, oral food challenges.