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Test ID FCUIX CU Index

Specimen Required

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.

Specimen Type: Serum

Collection Container/Tube: Red or SST

Submission Container/Tube: Plastic vial

Specimen Volume: 2 mL

Collection Instructions:

1. Draw 5 mL blood in a serum separator tube (SST) (plain, red-top tube is acceptable).

2. Separate from cells within 2 hours of draw. Send 2 mL of serum ambient in a plastic vial.

Method Name

Ex Vivo Challenge, Cell Culture and Histamine Analysis

Reporting Name

CU Index

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Ambient (preferred) 14 days
  Frozen  14 days
  Refrigerated  14 days

Reference Values

< 10.0


The CU Index test is the second generation Functional Anti-FceR test. Patient with a CU Index greater than or equal to 10 have basophil reactive factors in their serum which supports an autoimmune basis for disease.


Day(s) Performed

Monday and Thursday

Report Available

2 to 9 days

Performing Laboratory

Eurofins Viracor

Test Classification

This test was developed and its performance characteristics determined by Viracor Eurofins. It has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
FCUIX CU Index 63369-3


Result ID Test Result Name Result LOINC Value
FCUIX CU Index 63369-3