Which of the following conclusions can be drawn about a patient whose total IgE level was determined to be 150 IU/mL?

• A. Antigen-specific testing should be done.
• B. The patient will never have an allergic reaction.
• C. The patient may be subject to anaphylactic shock.
• D. The patient definitely has allergic tendencies.

Answer: (A)

Total IgE is a nonspecific marker of atopy, not a diagnostic test for allergy. A single elevated level doesn’t tell you which substances, if any, a patient is allergic to. The best next step is to perform antigen-specific testing (such as specific IgE tests or skin prick testing) to identify which allergens the patient may be sensitized to and to correlate these findings with the patient’s clinical history. Therefore, antigen-specific testing should be done.

The other conclusions aren’t supported by a total IgE value alone: a raised total IgE does not guarantee allergic reactions, it does not by itself indicate a risk of anaphylaxis, and it does not prove that the patient has allergic tendencies—it simply raises the possibility and warrants targeted testing to confirm sensitizations.