--- title: "When should a preliminary strand test be performed" description: "When should a preliminary strand test be performed? It is done before definitive hair drug testing to ensure sample suitability. Call (877) 731-6362 for details." author: "AMH Nationwide" date: "2026-08-28" tags: ["when should a preliminary strand test be performed"] canonical: "https://amhnationwide.com/when-should-a-preliminary-strand-test-be-performed/" last_updated: "2026-08-28" --- # When should a preliminary strand test be performed **By AMH Nationwide** | August 28, 2026 When should a preliminary strand test be performed? It is done before definitive hair drug testing to ensure sample suitability. Call (877) 731-6362 for details. --- When should a preliminary strand test be performed? This test is conducted to verify the adequacy and condition of hair samples before comprehensive drug analysis. It helps confirm sample integrity and suitability, reducing the chance of invalid results. Call (877) 731-6362 to arrange testing or for more information. TEST TIMING ## When should a preliminary strand test be performed? A preliminary strand test should be performed before the main hair drug test to confirm that the hair sample is sufficient in quantity and quality for analysis. This step is critical to avoid processing inadequate or compromised samples that could lead to inconclusive or invalid results. This test is typically requested when the sample collection is questionable due to factors like insufficient hair length, contamination, or cosmetic treatments that might affect the accuracy of the drug detection. Confirms sample adequacy before full testing Identifies contamination or damage that could alter results Helps laboratories decide if recollection is necessary WHO ORDERS ## Who typically orders a preliminary strand test? Employers, legal entities, and [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) departments often request a preliminary strand test to ensure that the hair sample collected meets the standards required for definitive drug testing. Individuals ordering tests may also request it if they have concerns about sample quality. Because hair testing is used to detect drug use over a 90-day window, ensuring the sample’s suitability before full analysis is important for reliable results. LAB PROCESS ## How do the labs handle a preliminary strand test? AMH Nationwide routes hair samples through five national lab networks: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, and ExperTox for preliminary strand testing. These labs assess the hair’s length, weight, and condition before proceeding to drug analysis. If the sample passes the preliminary test, it moves forward for drug screening. If it fails, the lab will notify the requester, and recollection may be advised. Every non-negative result is reviewed by a certified Medical Review Officer (MRO) to ensure accuracy and interpret findings appropriately. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## What is the detection window for hair drug testing? Hair drug testing, including preliminary strand tests, typically covers drug use over approximately 90 days. The hair sample usually needs to be at least 1.5 inches long to represent this timeframe. The preliminary strand test ensures that the collected hair can support analysis over this detection window. If the hair is too short or damaged, it may not reliably reflect drug use history. ## Ready to Schedule a Preliminary Strand Test? Contact AMH Nationwide to arrange hair drug testing with preliminary strand analysis. Call (877) 731-6362 to speak with a representative. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) DOT AND NON-DOT ## Is the preliminary strand test used for DOT-regulated testing? No, the Department of Transportation (DOT) requires [urine](https://amhnationwide.com/urine-drug-testing/) testing under federally certified protocols ([49 CFR Part 40](https://www.transportation.gov/odapc/part40)) for safety-sensitive positions. Hair testing, including preliminary strand tests, is used primarily for non-DOT roles. Employers outside DOT regulations may use hair testing to obtain a longer detection window and to supplement urine testing. PRICING ## How much does a preliminary strand test cost? Pricing for a preliminary strand test varies depending on the testing panel and detection window requested. Because it is part of the hair drug testing process, costs can differ by provider and lab network. To get an accurate quote for your specific needs, call (877) 731-6362. SAMPLE COLLECTION ## How is hair sample collection managed for the preliminary strand test? AMH Nationwide directs test requesters to one of our 20,000+ nationwide collection sites to obtain hair samples. We provide the lab order and collection instructions but do not offer online ordering. Collection technicians follow strict protocols to ensure samples meet lab requirements for both preliminary strand testing and definitive drug testing. AMH Reviewed & Maintained By AMH Nationwide Customer Service AMH Nationwide is BBB A+ accredited and routes every order through Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox, all of which use multiple lab certification agencies and standards such as [SAMHSA](https://www.samhsa.gov/workplace/drug-testing)-aligned laboratory protocols, the ANSI National Accreditation Board for forensic testing and calibration, the College of American Pathologists (CAP), and Clinical Laboratory Improvement Amendments (CLIA). Every non-negative screen is reviewed by a certified Medical Review Officer as part of standard processing before a result is released, and chain-of-custody documentation is maintained on every collection. This page does not constitute medical or legal advice. **Last updated:** July 2026 You May Also Need [Nail Drug TestingNo head or body hair available? A 5-panel fingernail test covers a similar look-back window.Learn more →](https://amhnationwide.com/5-panel-fingernail-drug-test/)[ChildGuard: Environmental ExposureConcerned about a child or loved one? ChildGuard screens for exposure to drugs in their environment.Learn more →](https://amhnationwide.com/5-panel-hair-drug-test-environmental-exposure-childguard/)[Shorten the Detection WindowShortened options like 30 and 60 day hair panels are also available, useful when a urine test’s 1-3 day window is too short.Learn more →](https://amhnationwide.com/30-day-hair-drug-test/)[Hair ETG Alcohol TestAlso need alcohol testing? The hair ETG test screens for alcohol use, and can be added to the same collection.Learn more →](https://amhnationwide.com/etg-and-peth/) Frequently Asked Questions ## Common Questions No, a preliminary strand test does not detect drug use. It only verifies that the hair sample is suitable for drug testing by assessing length, weight, and condition before full analysis. If a hair sample fails the preliminary strand test due to insufficient length or damage, the lab notifies the requester. A recollection is usually required to obtain a valid sample. Hair drug testing provides a longer detection window, typically up to 90 days, compared to urine testing. However, each method has specific uses and limitations depending on the testing purpose. All non-negative hair drug test results are reviewed by a certified Medical Review Officer (MRO) who evaluates the findings and ensures proper interpretation. Yes, chemical treatments like bleaching or dyeing can damage hair and affect the preliminary strand test by compromising the sample’s integrity or drug detection capability. AMH Nationwide coordinates testing and directs samples to one of five national lab networks for analysis. We do not perform testing onsite but manage the order and reporting process. Sources • [SAMHSA – Mandatory Guidelines for Federal Workplace Drug Testing Programs](https://www.samhsa.gov/workplace/drug-testing) • [U.S. DOT – 49 CFR Part 40 – Procedures for Transportation Workplace Drug and Alcohol Testing Programs](https://www.transportation.gov/odapc/part40) • [CDC – National Center for Health Statistics – Drug Use FastStats](https://www.cdc.gov/nchs/fastats/drug-use.htm) • [Quest Diagnostics – Employer Solutions, Hair Testing Methodology](https://www.questdiagnostics.com/) • [LabCorp – Occupational Testing Services](https://www.labcorp.com/) ## Ready to get started? AMH Nationwide provides the lab order and arranges collection nationwide. Every non-negative result reviewed by a certified Medical Review Officer. Call (877) 731-6362 or contact us. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) --- **Need a drug, alcohol, HIV or STD test?** AMH Nationwide is a national lab testing agency operating since 2004, with more than 20,000 collection sites across the United States. Hair, urine, fingernail and blood testing, panels from 5 through 19, for individuals and employers. - Call: (877) 731-6377 - Find a collection site: https://amhnationwide.com/locations/ - Full page: https://amhnationwide.com/when-should-a-preliminary-strand-test-be-performed/