Serum

Patients taking calcineurin inhibitors should stop their medication for 72 hours prior to draw. Patients on prednisone should be off their medication for two weeks prior to draw. If the specimen is to be held more than one week, it should be stored frozen.

Preferred Minimum: 1 mL serum
Absolute Minimum: 0.15 mL serum

2-5 business days from receipt of specimen at reference laboratory

The result is reported as an index value. The reference range for a healthy non-CU population is less than 10. Values greater than or equal to 10 indicate that donor basophils were stimulated by patient serum to release histamine. The larger the value the more histamine released.

Patients with a chronic form of urticaria who are positive (greater than or equal to 10) with the CU Index (Functional Anti-FcER test) have an autoimmune basis for their disease. A positive result does not indicate which autoantibody (anti-IgE, anti-FcERI or anti-FcERII) is present. In addition, the presence of histamine releasing factors in serum may cause a positive result. Studies with this CU Index (Functional Anti-FcER test) indicated that 41% of the CU patients were positive for this autoantibody, which is similar to the prevalence in published studies. The sensitivity and specificity are similar to previous reports.

This mailout test requires pathologist approval for orders during inpatient encounters. Mailouts staff will not process order without approval. The pathologist covering mailouts approval can be reached at pager #3724. If approval is given, the name of the pathologist can be selected in the drop-down menu to the right of the approval warning in Epic when ordering the test.

Ex Vivo Challenge, Cell Culture and Histamine Analysis

86376, 86800, 84443, 86352