Source library
Sources you can follow.
Every guide points back to original laboratory material. Use these resources for further reading.
- 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.
- USDTL · The long gameHair EtG and the effect of cosmetic hair treatments.
- USDTL · Urinary EtG and EtS researchResearch showing substantial differences in detection times between individuals.
- USDTL · Reservoir matrices (PDF)Why specimen results cannot establish an exact dose or time of use.
- Quest Diagnostics · CDT, test 16985Serum requirements, clinical context, and the assay reference interval.
How to read the graphs
The graphs compare approximate windows stated in the linked resources. Three months is represented as 90 days for display. Shaded ends show a published range, not a change in detection probability. Hair has a growth-related delay; a bar does not mean every day in the span is covered.
PEth and urine can remain detectable beyond the general ranges. CDT is excluded from time-span bars because Quest describes sustained-use association rather than a fixed detection window. There are no patient results or simulated concentration curves in these graphs.
Content was reviewed on October 26, 2026. USDTL and Quest Diagnostics are referenced as sources; their names do not imply that they authored or endorsed this guide.