CU Index
Use
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 supports the presence of basophil reactive factors in serum, indicative of an autoimmune etiology for urticaria. The test aids in understanding the pathophysiology of chronic urticaria and helps in determining the autoimmune contribution to the condition.
Special Instructions
Patients taking calcineurin inhibitors should halt medication 72 hours before blood draw, and those on prednisone should be off the medication for two weeks prior to the test. Ensure proper dosing and timing of any pre-test interventions as these may impact results.
Limitations
This test is specific for the autoimmune contribution to chronic urticaria. A positive CU Index indicates an autoimmune basis but does not specify which autoantibody is present among anti-IgE, anti-FceRI, or anti-FCERII. The result must be considered in conjunction with clinical findings and other laboratory results. Potential interfering substances or medications taken by the patient may lead to inconclusive results, and retesting or different diagnostic approaches may be advised.
New York Approved
Methodology
Cell-based / Cytometry (Flow Cytometry)
Biomarkers
LOINC Codes
- 63369-3
- 63369-3
Result Turnaround Time
2-9 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
Draw 5 mL blood in a serum separator tube (SST) or plain red-top tube. Separate from cells within 2 hours of draw. Send 2 mL of serum ambient in a plastic vial.
Patient Preparation
Patients taking calcineurin inhibitors should stop medication 72 hours prior to draw. Patients taking prednisone should be off their medication for 2 weeks prior to draw.
Causes for Rejection
Hemolysis: NA; Thawing: Warm OK; Cold OK; Lipemia: NA; Icterus: NA; Other: NA
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |