Are 0.9 and 2.1 index values considered positive in syphilis serology?

Any of the following requires urgent medical assessment: vision or hearing changes, severe headache, sudden weakness or paralysis, marked neck stiffness, a widespread rash especially affecting the palms or soles, or a painless genital or oral ulcer. If you have these signs go to the emergency department.

Index values are interpreted relative to the specific test method and the laboratory's designated cut-off. In routine practice for treponemal screening assays, a value around 0.9 is commonly considered negative or borderline, while a value around 2.1 is commonly considered positive; laboratory-specific thresholds may differ.

Check the exact test name on your report (for example EIA, CLIA, TPPA, TPHA, RPR, VDRL) and the laboratory's negative/borderline/positive cut-offs. A positive treponemal screening result is often followed by a non-treponemal test (RPR/VDRL) to assess activity and titers or by a second treponemal assay for confirmation. Tests done very soon after exposure can be affected by a window period; repeat testing may be needed.

Share your results with clinicians in: Infectious Diseases and Clinical Microbiology; Dermatology and Venereal Diseases; Family Medicine; or Obstetrics and Gynaecology, especially if pregnancy is possible or clinical concerns exist.

Verify the test type and lab cut-off on your report. While the result is unresolved, discuss partner evaluation and safer-sex practices with a healthcare professional. If symptoms develop or uncertainty persists, seek specialist assessment.