Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibodies, IgG & IgM by IFA
0050371
Ordering Recommendation
 
Mnemonic
RMSF G/M
Methodology
Semi-Quantitative Indirect Fluorescent Antibody
Performed
Mon-Fri
Reported
1-5 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
  
Collect
Serum separator tube.  
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.1 mL) Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Mark specimens plainly as acute or convalescent.  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
Contaminated, hemolyzed, or severely lipemic specimens.  
Remarks
  
Stability
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)  
Reference Interval
 
 
Test Number Components Reference Interval
0050369Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibody, IgG Less than 1:64: Negative -​ No significant level of Rickettsia rickettsii Antibody, IgG detected.
1:64 -​ 1:128: Low Positive -​ Presence of Rickettsia rickettsii Antibody, IgG detected, suggestive of current or past infection.
1:256 or greater: Positive -​ Presence of Rickettsia rickettsii Antibody, IgG suggestive of recent or current infection.
0050372Rickettsia rickettsii (Rocky Mountain Spotted Fever) Antibody, IgM Less than 1:64: Negative -​ No significant level of Rickettsia rickettsii Antibody, IgM detected.
1:64 or greater: Positive -​ Presence of Rickettsia rickettsii Antibody, IgM detected, which may indicate a current or recent infection; however, low levels of IgM antibodies may occasionally persist for more than 12 months post-​infection.
 
Interpretive Data
The best evidence for current infection is a significant change on two appropriately timed specimens, where both tests are done in the same laboratory at the same time.

The CDC does not use IgM results for routine diagnostic testing of Rocky Mountain Spotted Fever, as the response may not be specific for the agent (resulting in false positives) and the IgM response may be persistent from past infection.  
Note
 
CPT Code(s)
86757 x2
Components
Component Test Code*Component Chart Name
0050369Rocky Mt Spotted Fever IgG
0050372Rocky Mt Spotted Fever IgM
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Rickettsia
  • RMSF
  • Rocky Mountain Spotted Fever