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This is a sendout test. Please note that turnaround time is defined as the anticipated time from set up day to results release.
S52235: Rabies Vaccine Response End-point Titer Print View
Rabies Response     IU/mL 

1 Serum 2 (1) mL   Frozen - 30 Day(s)/Refrigerated - 10 Day(s)  
  CSF 3 (1) mL   Refrigerated - 10 Day(s)/Frozen - 30 Day(s)  

What is "the RFFIT"? RFFIT stands for Rapid Fluorescent Foci Inhibition Test. It is a serum neutralization (inhibition) test, which means it measures the ability of rabies specific antibodies to neutralize rabies virus and prevent the virus from infecting cells. These antibodies are called rabies virus neutralizing antibodies (RVt4A). The RFFIT does not measure the amount of rabies specific antibodies but the neutralizing activity of the antibodies present in the serum. In the test, your serum (the non- cellular portion of your blood) is first diluted fivefold (1 part serum in 4 parts diluent). Further (serial fivefold) dilutions are performed, each of which contain less and less of your serum. These serum dilutions are mixed with a standard amount of live rabies virus and incubated. Whatever RVNA is present will neutralize the virus. Next, some tissue culture cells are added and the serum/virus/cells are incubated together. Whatever rabies via's is left (i.e., that which has not been neutralized by the antibody in your serum), will infect the cells and this can be seen under the microscope through the use of specific staining. Calculation of the endpoint titer is made from the percent of virus infected cells observed on the slide. What does your result tell you? The RFFIT test can be used in two ways: to determine a RVNA titer (eg., 1:5) or to determine a value for R\NA concentration (e.g., 0.1 IU/mL). The IU stands for international unit and is calculated from the titer by comparing it against a standard reference serum. We use the following formula: sample titer divided by the reference serum titer, multiplied by the IU/mL value of the reference serum. Example: Your titer is 1:100, the reference serum titer is 1:200, and the value of the reference serum is 2.0 IU/mL. Using the formula: (100/200) X 2.0 IU/mL= 10 IU/mL the potency of RVNA in your serum is therefore 1.0 IU/mL. Because the RFFIT

*Lab will not release results without collection date.
Setup Schedule
Monday, Wednesday, Thursday

Reported (Analytical Time)
21 days

CPT Code

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Methodology: Rapid Fluorescent Foci Inhibition Test (RFFIT)
Rejection criteria: Gross hemolysis, Grossly lipemic
Specimen requirements:
Preferred 2 mL (1 mL minimum) serum or 3-5 mL (1 mL minimum) CSF collected in a no additive Red-Top tube
Stability: Room temperature: Unacceptable;
Refrigerated: 10 days;
Frozen: 30 days ** This test is not available for Florida patient testing. Please use test code 91810 - Rabies RFFIT Serology End Point Titer for Florida patient testing.**

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For test information, please call Client Services at 800-421-4449.

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