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Test Code LAB6640 Q Fever Antibody, IgG and IgM, Serum

Additional Codes

 

Test Name in EPIC EPIC Test Code Mnemonic Mayo Test ID
Q FEVER AB, IGG AND IGM, S LAB6640 QFEVR QFP

 

Reporting Name

Q Fever Ab, IgG and IgM, S

Useful For

Diagnosing Q fever

Testing Algorithm

See Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology in Special Instructions.

Method Name

Indirect Immunofluorescence

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Container/Tube: 

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  7 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

NA

Other

NA

Reference Values

Q FEVER PHASE I ANTIBODY, IgG

<1:16

 

Q FEVER PHASE II ANTIBODY, IgG

<1:16

 

Q FEVER PHASE I ANTIBODY, IgM

<1:16

 

Q FEVER PHASE II ANTIBODY, IgM

<1:16

Day(s) and Time(s) Performed

Monday through Friday; 9 a.m.

CPT Code Information

86638 x 4

LOINC Code Information

Test ID Test Order Name Order LOINC Value
QFP Q Fever Ab, IgG and IgM, S 77175-8

 

Result ID Test Result Name Result LOINC Value
80965 Q Fever Phase I Ab, IgG 34716-1
24011 Q Fever Phase II Ab, IgG 34717-9
81115 Q Fever Phase I Ab, IgM 9710-5
24009 Q Fever Phase II Ab, IgM 9711-3
24010 Interpretation 69048-7

Method Description

An indirect immunofluorescence test is used for the measurement of IgM and/or IgG antibodies to Coxiella burnetii. Specific antibodies present in the serum of the patient react with rickettsial cells that have been previously fixed on a glass microscope slide. Fluorescein-labeled antihuman IgG or IgM conjugate is used to stain specific antibody bound to the substrate cells. The slides are examined with a fluorescence microscope for characteristic, apple-green fluorescence of the infected cell.(Edligner B: Immunofluorescence serology: a tool for prognosis of Q fever Diagn Microbiol Infect Dis 1985;3:343-351; Package inserts: Q fever IFA IgG Focus Diagnostics, Inc., Cypress, CA; Q fever IFA IgM, Focus Diagnostics, Inc., Cypress, CA)

Cautions

Serologic responses are time-dependent. Specimens drawn too early in the disease may not have detectable antibody levels. A second specimen 2 to 4 weeks later may be necessary to detect antibody.

Specimen Retention Time

14 days

Test Classification

This test has been cleared or approved 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.

Interpretation

Phase I antibody titers greater than or equal to phase II antibody titers are consistent with chronic infection or convalescent phase Q fever.

 

Phase II antibody titers greater than or equal to phase I antibody titers are consistent with acute/active infection.

 

A negative result argues against Coxiella burnetii infection. If early acute Q fever infection is suspected, draw a second specimen 2 to 3 weeks later and retest.

 

In Q fever sera, it is common to see IgG titers of 1:128 or greater to both phase I and phase II antibody titers. IgG class antibody titers appear very early in the disease, reaching maximum phase II titers by week 8 and persisting at elevated titers for longer than a year. Phase I titers follow the same pattern, although at much lower levels, and may not be initially detected until convalescence.

 

In Q fever sera, it is common to see IgM titers of ≥1:64.

 

IgM class antibody titers appear very early in the disease, reaching maximum phase II titers by week 3 and declining to very low levels by week 14. Phase I titers follow the same pattern, although at much lower levels, and may not be initially detected until convalescence.

Clinical Information

Q fever, a rickettsial infection caused by Coxiella burnetii, has been recognized as a widely distributed zoonosis with the potential for causing both sporadic and epidemic disease. The resistance of Coxiella burnetii to heat, chemical agents, and desiccation allows the agent to survive for extended periods outside the host.

 

The infection is spread by the inhalation of infected material, mainly from sheep and goats. They shed the organism in feces, milk, nasal discharge, placental tissue, and amniotic fluid.

 

The clinical spectrum of disease ranges from unapparent to fatal. Respiratory manifestations usually predominate; endocarditis and hepatitis can be complications.

 

During the course of the infection, the outer membrane of the organism undergoes changes in its lipopolysaccharide structure, called phase variation. Differences in phase I and phase II antigen presentation can help determine if the infection is acute or chronic:

-In acute Q fever, the phase II antibody is usually higher than the phase I titer, often by 4-fold, even in early specimens. Although a rise in phase I as well as phase II titers may occur in later specimens, the phase II titer remains higher.

-In chronic Q fever, the reverse situation is generally seen. Serum specimens drawn late in the illness from chronic Q fever patients demonstrate significantly higher phase I titers, sometimes much greater than 4-fold.

-In the case of chronic granulomatous hepatitis, IgG and IgM titers to phase I and phase II antigens are quite elevated, with phase II titers generally equal to or greater than phase I titers.

-Titers seen in Q fever endocarditis are similar in magnitude, although the phase I titers are quite often higher than the phase II titers.

Analytic Time

Same day/1 day