Interactive testing simulator
See how the tests fit together.
Choose recent days, older history, or both. Add tests to explore their approximate windows and where they overlap.
Your comparison
Recent + past
A bar is an approximate reference span, not proof of detection on every day. Empty space is not proof of clearance.
What about “right now”?
Here, “recent” means a history of use before collection. These windows do not establish current impairment. PEth is not a blood alcohol concentration test. Confirm the appropriate test for an immediate question with the ordering professional.
What the simulator assumes
How are overlap and hair history shown?
All specimens are collected today. The highlighted band is your chosen period; changing it zooms the timeline automatically. Urine and PEth overlaps are intersections of the displayed reference spans, not probabilities or guaranteed detection. Hair is shown as an outlined, patterned band for approximately three months (90 days on this chart). It contributes historical context, but is excluded from day-specific overlap calculations because hair growth and sampling do not provide a dated record. The band reaching “today” does not imply immediate detection.
Why doesn’t CDT fill a gap?
Quest describes CDT as an indirect marker associated with sustained heavy use, with other medical factors affecting interpretation. It adds a different kind of context, not a fixed number of days on the timeline. Adding CDT does not extend a window.
Does combining tests prove continuous abstinence?
No. Windows vary with the substance, specimen, cutoff, use pattern, and person. Even overlapping tests can miss use, and a negative result does not certify every day in a period. This tool does not choose a court-compliant testing plan; confirm the exact tests, collection requirements, and any ongoing schedule with the ordering party.
What is saved or shared?
The controls run in your browser. There are no names, results, or case notes to enter. “Share this comparison” saves only the test choices and relative period in the link and QR code, so someone else can open the same example.
Laboratory sources behind the simulator
- USDTL · Hair drug testingScalp hair, specimen collection, and the approximate three-month window.
- USDTL · PEth and dried blood spot testingBlood specimens and the variability of PEth detection.
- USDTL · Urine testingLaboratory urine testing, panel selection, and confirmation.
- USDTL · Made in the bloodAlcohol biomarkers and limitations of urine and hair testing.
- Quest Diagnostics · CDT, test 16985Serum requirements, clinical context, and the assay reference interval.
Reference information reviewed October 26, 2026. This simulator is an educational interpretation of these resources, not a laboratory-validated prediction tool.