For determining efficacy of clinical interventions for detoxification, a pretest/post-test approach should be considered, which is how effectiveness is studied in clinical trials.
Usually this involves retesting at a fixed time after the intervention period. A typical posttest approach would be to retest within 7-14 days of discontinuation of treatment.
This may be particularly relevant with toxin testing and detoxification because often the patient has ongoing toxic exposures which may be confounders when retesting 1 month, 3 months, or later (i.e., they are still accumulating/re-accumulating toxins).
