Rickettsia rickettsii Antibody, IgG & IgM
Label Mnemonic: RMSGM
Epic Lab Code: LAB7511
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Specimen Instructions:
Acute and convalescent specimens must be labeled as such; parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Please mark specimen plainly as "acute" or "convalescent."
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
1 mL serum in a red top tube
Rejection Criteria:
Severely lipemic, contaminated, or hemolyzed specimens.
Turn Around Time:
1-4 days upon receipt at reference laboratory
Reference Range:
Rickettsia rickettsii 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. Rickettsia rickettsii 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.
Methodology:
Semi-Quantitative Indirect Fluorescent Antibody
CPT Code:
86757 x2