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CU Index®*

Test Code: 2103
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Clinical Utility

Patients with a chronic form of urticaria who are positive (> 10) with the CU index® have an autoimmune basis for their disease. A positive result does not indicate which autoantibody (anti-IgE, anti-FceRI or anti-FceRII) is present.

About Chronic Urticaria

Chronic urticaria is a common skin disorder affecting 0.1 to 1% of the general population. It is characterized by recurrent, transitory, pruritic erythematous wheals present for at least 6 weeks.1 The impact of chronic urticaria on the quality of life can be significant. Kaplan and others have demonstrated that in 30–50% of these chronic urticaria patients there is an autoimmune etiology with autoantibodies against IgE, FcεRI or FcεRII (CD23).2-6 It is presumed that these autoantibodies bind to the surface of mast cells and basophils and initiate a signal transduction cascade that results in secretion of histamine and other mediators. The treatment course for the autoimmune form of the disease is often different from treatment for acute and transient urticaria or idiopathic chronic urticaria. Drugs that modulate the basic immunological aspects of the disease (e.g., methotrexate, calcineurin inhibitors) may be considered if an autoimmune etiology is established.7,8



Ex-Vivo Challenge and cell culture: Donor blood cells are incubated with patient serum, a negative control and a positive control. Following the ex-vivo challenge, the cells are centrifuged and the supernatant is recovered for assay of histamine released. Histamine Analysis: Using a quantitative enzyme immunoassay, the histamine released into the supernatant is measured and compared to the total histamine in the basophils. This test has not been cleared or approved for diagnostic use by the U.S. Food and Drug Administration.

2-5 business days from receipt of specimen

Specimen Type Order Code CPT Code NY Approved Volume Assay Range Special Instructions
serum 2103 86352 Yes

1 mL (min. 150 uL)


  • Collect 3-5 mL whole blood in a serum separator tube (SST).
  • Centrifuge specimen within 2 hours of draw to pellet cells below the gel.
  • Patients taking calcineurin inhibitors should stop their medication for 72 hours prior to draw. Patients taking Prednisone should be off their medication for 2 week prior to draw
  • Can be shipped at ambient or frozen temperature Monday through Friday.


Specimens are approved for testing in New York only when indicated in the Specimen Information field above.

The CPT codes provided are based on Viracor Eurofins' interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for general informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Viracor Eurofins assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.

*Patent No.: US 7, 824, 877. Use of intellectual property owned by Viracor Eurofins to recreate, replicate or attempt in any way to determine the structure or composition of a patented or proprietary assay ("Product") is strictly prohibited and may be considered patent infringement. Further, modifying the Product, creating derivatives thereof or improvements thereon, or use of Viracor Eurofins' Products and test results to evaluate, validate or certify a competing assay, may also be considered patent infringement. Please contact Viracor Eurofins' at 800-305-5198 with any questions regarding its patents, or visit for general information on patent and IP law policy.


1 Greaves M. Chronic Urticaria. J Allergy Clin Immunol. 2000 Apr;105(4):664-72.

Tong LJ, Balakrishnan G, Kochan JP, Kinet JP Kaplan AP. Assessment of autoimmunity in patients with chronic urticaria. J Allergy Clin Immunol. 1997 Apr;99(4):461-5.

Ferrer M, Kinet, JP Kaplan AP. Comparative studies of functional and binding assays for IgG anti-FceRIα (α-subunit) in chronic urticaria. J Allergy Clin Immunol. 1998 May;101(5):672-6.

Puccetti A, Bason C, Simeoni S, Millo E, Tinazzi E, Beri R, et al. In chronic idiopathic urticaria autoantibodies against FceRII/CD23 induce histamine release via eosinophil activation. Clin Exp Allergy. 2005 Dec;35(12):1599-1607.

 Soundararajan S, Kikuchi Y, Joseph K, Kaplan AP. Functional assessment of pathogenic IgG subclasses in chronic autoimmune urticaria. J Allergy Clin Immunol. 2005 Apr;115(4):815-21.

Platzer MH, Grattan CEH, Poulsen LK, Skov PS. Validation of basophil histamine release against the autologous serum skin test and outcome of serum-induced basophil histamine release studies in a large population of chronic urticaria patients. Allergy. 2005 Sep;60(9):1152-6.

 Marsland AM, Soundararajan S, Joseph K, Kaplan AP. Effects of calcineurin inhibitors on an in vitro assay for chronic urticaria. Clin Exp Allergy. 2005;35(5):554-9.

 Grattan CE, O’Donnell BF, Francis DM, Niimi N, Barlow RJ, Seed PT, Kobza Black A, Greaves MW. Randomized double-blind study of cyclosporine in chronic ‘idiopathic’ urticaria. British Journal of Dermatology. 2000 Aug;143(2):365-72.

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