When should you order a Lyme titer?
The Journal of Family Practice. 2005 December;54(12):1084-1088
December 1, 2005|Family Medicine
Author and Disclosure Information
Guidelines established by a joint CDC/Association of State and Territorial Public Health Laboratory Directors commission require a 2-tiered laboratory approach to diagnosis.2 A highly sensitive initial test (ELISA) is followed by a highly specific supplemental test (Western blot). These guidelines have good clinical applicability (overall sensitivity 50%, specificity 100%).10 The relatively low sensitivity is likely due to antibiotic treatment of several subjects resulting in reduced humoral response.
TABLE
Pretest probability scenarios for suspected Lyme disease
| CLINICAL SCENARIO | TEST? | RATIONALE |
|---|---|---|
| Erythema migrans | No | Pretest probability high; clinical diagnosis of Lyme disease (treat without testing) |
| Signs/symptoms of disseminated Lyme disease, live in endemic region | Yes | Pretest probability intermediate; high prevalence yields high PPV |
| Signs/symptoms of disseminated Lyme disease, live in non-endemic region | Yes | Pretest probability intermediate; cost-effective |
| Nonspecific myalgias | No | Pretest probability too low |
| Asymptomatic patient | No | Pretest probability too low |
| Empiric antibiotic response; treatment | No | Antibiotic treatment decreases humoral testing not cost effective |
| Test-of-cure | No | Test remains positive after treatment |
| Immunized | No | ELISA will be positive (Western blot could assess exposure) |
