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Test Code Billings Clinic: 8742 Mayo: SFGP Spotted Fever Group Antibody, IgG and IgM, Serum

Reporting Name

Spotted Fever Group Ab, IgG, IgM, S

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Aids in the diagnosis of spotted fever group rickettsial infections

Method Name

Immunofluorescence


Specimen Required


Container/Tube: 

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL


Specimen Type

Serum

Specimen Minimum Volume

0.2 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

Reference Values

IgG: <1:64

IgM: <1:64

Reference values apply to all ages.

Interpretation

This test detects reactivity to the group-specific rickettsia. For example, antibody reactivity to the Rickettsia rickettsii will also react with other organisms within the spotted fever group.

 

IgG

≥1:256:

-Serum end point titers of ≥1:256 are considered presumptive evidence of recent or current infection by organisms of appropriate rickettsial antigen group.

 

<1:256 and ≥1:64:

-Single serum end point titers ≥1:64 and <1:256 are suggestive of infection at an undetermined time and may indicate either past infection or early response to a recent rickettsial infection.

-A 4-fold or greater increase in IgG titer between 2 serum specimens drawn 1 to 2 weeks apart and tested in parallel is considered presumptive evidence of a recent or current infection.

-In patients infected with organisms within the rickettsial groups, IgG antibody is generally detectable within 1 to 2 weeks of onset of symptoms, peaking within 1 to 2 months and declining thereafter. Following prompt antimicrobial treatment, titers generally decline below detectable levels within 8 to 11 months. With relapse, prior immunization, or delayed antibiotic treatment, IgG levels may remain elevated for more than a year postonset.

 

IgM

≥1:64:

-Titers of ≥1:64 are considered presumptive evidence of recent or current infection by organisms of appropriate rickettsial antigen group.

 

<1:64:

-Titers <1:64 suggest that the patient does not have an acute rickettsial infection.

-IgM class antibody is transiently detected within 1 to 2 weeks of onset of symptoms, usually declining rapidly within 3 months following prompt antibiotic treatment. These levels will also be elevated for an extended period with relapse, prior immunization, or delayed antibiotic treatment.

Day(s) and Time(s) Performed

Monday through Friday; 9 a.m.

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86757 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SFGP Spotted Fever Group Ab, IgG, IgM, S 90260-1

 

Result ID Test Result Name Result LOINC Value
84342 Spotted Fever Group Ab, IgG, S 5313-2
84346 Spotted Fever Group Ab, IgM, S 5315-7

Testing Algorithm

See Acute Tick-Borne Disease Testing Algorithm in Special Instructions.

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.