Family Nurse Practitioner Exam

What does anergy testing evaluate in patients screened for TB who are immunocompromised?

1. Apply Candida or mumps antigen on the left forearm only

2. Apply Candida or mumps antigen on the right forearm and PPD on the left forearm

3. Mix Candida or mumps antigen with PPD and apply it to both forearms

4. Apply the mumps antigen before the PPD on the left forearm

The correct answer is: Apply Candida or mumps antigen on the right forearm and PPD on the left forearm

Anergy testing is designed to evaluate the immune response in patients who may be immunocompromised, particularly in the context of tuberculosis (TB) screening. In these patients, standard tuberculin skin tests, such as the PPD test, may yield false-negative results due to a diminished immune response. The correct approach involves applying a non-TB antigen, such as Candida or mumps, to one forearm, while simultaneously applying the PPD to the other forearm. This ensures that the clinician can assess the patient's ability to mount an immune response to a known antigen in the presence of the PPD. If the patient shows a reaction to the non-TB antigen but does not react to the PPD, this may indicate an anergic state due to immunocompromise. Using this method allows for a more accurate evaluation of the patient's potential for developing TB, as the response to the non-TB antigen indicates that the immune system is at least partially functional. If there is no response to the PPD despite a proper response to the non-TB antigen, it suggests that the patient's immune system is not capable of responding adequately to TB exposure. Thus, combining the PPD test with the application of a non-TB antigen to assess immune