In vivo allergy testing measures the processes and reactions of the allergic response "within the body."

Skin testing methodologies, in vivo allergy testing, include the following types:

• Skin Prick Test
• Intradermal (Subcutaneous) Test
• Challenge (Provocation) – limited to certain allergens

Some time ago, it was discovered that in vitro allergy testing, or testing for allergy by removing a blood sample from the patient and measuring the allergic reaction in an artificial environment (the test tube), provided alternative diagnostic procedures for the patient and quantifiable results for the laboratory professionals.

The most common in vitro methodologies are:

• RIA (Radioimmunoassay), or frequently called a RAST test. RAST is an acronym for radioallergosorbent test, manual and/or automated
• EIA (Enzyme Immunoassay), manual and/or automated
  

Advantages of In Vitro Allergy Testing

• Greater patient comfort during diagnostic process
• One blood draw
• Not dependent on skin conditions
• Patients on anti-histamines need not discontinue their medication
• Diagnosis occurs in fewer visits
• Not dependent on technique used by person performing the skin test
• Quantitative results facilitate transition into immunotherapy at ideal levels
• Saves time
• Minimizes potential for adverse reaction to immunotherapy
• Enables managed care organizations to standardize diagnostic process
• Shortens treatment time span, thereby lowering costs
• Collateral benefits to managed care organizations
• Lowers immunotherapy costs
• Reduces emergency room visits
• Helps patients to avoid allergenic triggers of acute asthmatic episodes
• Reduces office visits