Background image

PEth Resources

PEth Resources

To view the PEth Testing Panels and Collection Instructions, click here.

PEth Videos

Watch Video

Blood Spot Collection Training Video

Watch Video

CCDG Presentation

Watch Video

Direct Alcohol Biomarkers – EtG and PEth Webinar

Watch Video

Direct Biomarkers of Alcohol Use by Dr. Adam Negrusz

Watch Video

Long-term Biomarkers for monitoring DUI/OWI offenders

Watch Video

Why Test For PEth in Blood

Watch Video

Wisconsin Counties Use Long-Term Alcohol Biomarker Testing

View All Videos

PEth Infographics

View All Infographics

USDTL PEth Test In the News

View All USDTL Tests In the News

PEth Articles

View All Articles 

USDTL PEth Research

View All USDTL Research

PEth Poster Presentations

View All Poster Presentations

USDTL Assisted PEth Research

View All USDTL Assisted Research

PEth Hair Research

View All Foundational Research

PEth White Papers

View All White Papers

PEth Slide Presentations

There are currently no Slide Presentations. Please check back later.

View All Slide Presentations

PEth Announcements

View All Announcements


*Click the green and white plus sign beside each question to view the answer.

Are the PEth collection supplies CLIA-waived?

The collection supplies that we have are not CLIA-waived, as we are a CLIA accredited laboratory and must follow all accreditation standards.

Are you aware of any other labs splitting specimens for PEth or sending two specimen cards filled with dried blood for testing?

There are no other labs that do commercial dried blood spot PEth testing, so there are no labs for comparison.

Can a second test of a different specimen type be used to prove that a previously taken test was inaccurate?

No. The results of any second collected specimen have absolutely no bearing on the validity of the results of the first collected specimen. Furthermore, each matrix has its own advantages, disadvantages and limits of interpretation.

Can a single serving of ethanol alcohol (12 oz. beer, 5 oz. wine), cause a positive Phosphatidylethanol (PEth) using a 20 ng/mL cut-off in whole blood or dried blood spot?

The literature suggests that it requires multiple servings of ethanol on a single occasion to produce a positive PEth result. PEth has a half-life of approximately 4.5 days.

Can the use of isopropanol (rubbing alcohol) containing product explain a positive PEth result?

There are zero instances in the scientific literature (over 25,000 articles) of anything other than consumption of ethanol creating Peth results.

Can we order just the blood spot cards?

Yes, during your account setup process just inform us that you will only need the blood spot cards.

Can we purchase the collection supplies for training purposes?

We do not sell collection supplies. All account set-up paperwork must be completed before we ship the supplies to your facility.

Can we put blood spot cards into a sealed plastic bag?

Before placing blood spot cards into a sealed plastic bag, you MUST allow the card to dry for one full hour. Once dry, you can place dried blood spot cards in a plastic bag but you MUST include desiccant packs to reduce the moisture in the bag. It is highly recommended that the cards are placed in a non-plasticized envelope for transport when possible to avoid any issues with moisture.

Can we transfer whole blood specimen to the blood spot card?

Whole blood can be submitted for PEth testing by sending in the whole blood tube. We do not recommend transferring blood collected under a chain of custody via venipuncture to a dried blood spot card.

Do you have any recommendations on how to ship specimens internationally?

We are not able to help with any of the shipping coordination or additional questions regarding international testing as we do not know the local laws.

Do you require a Chain of Custody Form for research specimens?

No. Chain of Custody Forms are not used for research specimens.

A manifest form is required in this case. Identification numbers and dates are required on the manifest. Click here to see a sample manifest form.

Please note that:

  • ID numbers on the manifest must match the ID on the specimens.
  • 2 unique numbers are preferred, if not possible, one unique number is acceptable.

Does the sample need to be frozen?

No, the sample may be shipped ambient.

Have results been used in court cases?

Yes, the analysis of a number of tissue types for the presence of drugs of abuse has been used in every state for decades. Specifically, our umbilical cord testing has been used to provide evidence of drug use by the mother in numerous states. Additionally, the detection of drug in umbilical cord was used as evidence of maternal drug consumption in a murder case in South Carolina and that interpretation was upheld on appeal to the SC Supreme Court.

Have you ever had any challenges to positive PEth test results in whole blood and/or dried blood spot?

Extensive research has helped create a good understanding of PEth and how it can be utilized both in research and commercially. This has helped eliminate major challenges that other, less researched assays, might face.

How do PEth results differ from Urine EtG/EtS results?

Recent studies have indicated that low-level positive EtG results can be produced by certain agents like hand sanitizers and mouth wash (incidental exposure). Research indicates that the volume of alcohol required to trigger a positive PEth result is far above the level available from incidental exposure.

How does a PEth test result correlate with “dangerous” versus “social” drinking?

The testing can only detect whether PEth is present in the specimen, it cannot determine time, dose, or frequency of use. The literature suggests that it requires multiple servings of ethanol on a single occasion to produce a positive PEth result.

How much blood is required for a PEth testing specimen?

5 individual large drops on a dried blood spot collection card or 5 milliliters of whole blood collected in a gray-top collection tube containing anticoagulant.

Is testing PEth in dried blood spot and whole blood the same price?

Yes, the price is the same whether it is whole blood or dried blood spot.

Is there a proportion of consumption related to each increasing result? i.e. is 100 ng/mL 5 times more consumed than a 20 ng/mL result?

Testing can only detect whether PEth is present in the specimen, it cannot determine time, dose, or frequency of use. PEth has a half-life of 4.5 days so the results are contingent on when the donor last drank and how much they have been drinking.

Is there a specific shipping company we would need to use or is that at our discretion?

You may use any shipping courier of your choice.

Is there a timeframe in which collected PEth specimens can no longer be tested for research purposes?

With strictly research specimens, our laboratory has more flexibility regarding testing timeframes. In general, specimens should not be tested beyond their stated timeframe for stability. The Sponsor should note that any results from testing specimens beyond their stated timeframe for stability can be less reliable.

Should I keep the collected dried blood spot specimens in a cooler or just at room temperature?

Please keep specimens at the normal air-conditioned lab temp ±26 degrees Celsius or in the fridge.

What does a positive PEth mean? Does it measure only heavy/binge drinking or will it be positive after consuming a drink per day over a few days?

A positive PEth result means that the donor has consumed ethanol sometime during the last 2-4 weeks (approximately).

What does USDTL provide in the PEth dried blood spot collection supplies?

  • 2 blood spot lancets
  • 2 tamper-evident seal
  • 2 non-ethanol based alcochol pads
  • 1 blood spot card
  • 1 blood spot drying box

What is the length of time PEth dried blood spot specimens can be stored while still maintaining their integrity?

  • Room Temp = 1 year
  • Refrigerated = 1 year
  • Frozen = 1 year at 20ºC (-4ºF)

What is the longest time PEth will remain positive after problem drinking stops?

The Peth test is designed to detect heavy drinking up to approximately 2-4 weeks prior to collection. This is because PEth has an average half-life is 4.5 days. This means that every 4.5 days the level of Peth is cut in half. For example: If an average person with a PEth level of 1000 ng/mL stops drinking, it would take approximately 2.5 weeks for them to fall below the 20 ng/mL cut-off level.

What is the minimum shipment requirement for PEth specimens for research purposes?

Please send at least 10 or more specimens per batch; preferably overnight with tracking capability. You can use any courier of your choice. Please have specimens arrive at USDTL between Monday and Friday.

What is the window of detection for PEth?

Up to approximately 2-4 weeks depending on the starting concentration of PEth.

Which phosphatidylethanol species do you measure during PEth testing?

Our PEth testing in dried blood spots measures the 16:0/18:1 PEth species.

With 5 dried blood spots, are all 5 spots used for testing PEth?

We typically use 2-3 of the blood spots for testing (assuming all five circles are filled). Ideally, there will be 1-2 blood spots left over and stored in the event a retest is requested.

View All FAQs

Contact USDTL