Cut-Off Levels

Rather than just detecting the presence of the drug, drug testing normally involves establishing the concentration of a drug above a certain level. A “cut-off level” is the concentration at (or above) which is deemed positive by a laboratory analysis for that drug. So why have cut-off levels at all? Cut-offs exist in order to standardise laboratory drug tests to one another (so that the sensitivity of measurement equipment is not a concern), minimise false positives and also to exclude defences which are base upon factors such as passive inhalation.

In Australia and New Zealand cut-off levels for a number of drug classes have been determined by expert committees, which are published as “Standards”. It is also important to note that cut-off levels differ between many countries. For example the cut-off level for amphetamine urine testing in the United States is 500 ng/mL, whereas the cut-off level in Australia for the same drug is 300 ng/mL. In this case the difference is significant; the US level is almost 100 % higher than Australia!

Organisations may also adopt particular cut-off levels for various drug classes which means that anybody purchasing a home test kit should check the relevant cut-off level that might apply prior to selecting a particular test. In Australia the cut-off levels detailed below, published in AS/NZS 2308:2008, are the most likely to apply.

Australian Cut-Offs

The cut-off levels of various drugs and/or their metabolites are defined by the Australian standard AS/NZS 4308:2008, which describes procedures for specimen collection and
the detection and quantitation of drugs of abuse in urine. Drug Test Direct’s complete range of drug tests comply with this standard and the levels are shown below for your convenience.

Code Test Drug Cut-Off Level
AMP Amphetamine 300 µg/L
BZO Benzodiazepines 200 µg/L
COC Cocaine Metabolites 300 µg/L
MET Methamphetamine 300 µg/L
OPI Opiates 300 µg/L
THC Cannabis Metabolites 50 µg/L

Period of Detection

The period of detection for a particular drug describes how it is possible to measure the presence of the drug (or it’s metabolites) following administration. This is an extremely subjective matter, which can be influenced by many different factors.

For example, let’s consider marijuana. Generally THC and its metabolites are detectable for the longest time out of all drugs of abuse. This is because the molecules are highly fat soluble. Because everybody’s metabolism is different the time it takes to burn the fat (which determines the period of detection), differs accordingly. Add to this influences such as the strength of the marijuana consumed, the frequency and method of ingestion and other factors and it becomes impossible to put an exact figure on the actual period of detection.

For these reasons please be aware that the tables below are presented as a guide only. For further information and reading you might like to look here.

Detection Tables

Please note that the drug detection times provided in table below are a guide only. Dugs Test Direct accept no responsibility for the outcome of results based upon using the information below. For further information see out disclaimer.

Code Substance Detection Time
Urine Saliva
AMP Amphetamine 1–3 days 12 hours
BZO Benzodiazepines 1–7 days 16–48 hours
COC Cocaine Metabolites 1–3 days 2–5 days
MET Methamphetamine 1–3 days 1–3 days
OPI Opiates 1–3 days 1–3 days
THC Cannabis Metabolites 1 day–2 months 1–2 days

Interfering Substances

Drug Tests Direct screening kits all immunoassay methodology to undertake a test, which means that functional groups on related moieties may also interact with the reagents and give rise to false positives. Commonly this can occur when somebody undergoing treatment for a particular medical condition and is taking a certain class of related drugs. It’s simply not possible to determine every interfering substance or scenario that would give rise to such a situation, but we hope the table below provides a helpful indication. If, following a test you have questions please don’t hesitate to give us a call and please note that all information is provided under out disclaimer.

Code Substance Medical Uses Potential Interfering Substances
AMP Amphetamine Attention Deficit Hyperactivity Disorder (ADHD), obesity, narcolepsy
BZO Benzodiazepines
COC Cocaine Metabolites Local anaesthetic, vasoconstrictor (unavailable in Australia)
MET Methamphetamine ADHD, obesity, narcolepsy (not available for medical use in Australia)
OPI Opiates Analgesic, antitussive, treatment for dependence Methodone, morphine, codeine, neurpofen plus
THC Cannabis Metabolites None in Australia

What is AS/NZS 4308:2008?

Drug testing within Australia and New Zealand is governed by a standard, known as AS/NZS 4380:2008, which describes procedures for specimen collection and the detection and quantitation of drugs of abuse in urine. It provides guidance and best practice recommendations on procedures such as the collection site, transportation, security, chain of custody, cut-off levels and storage requirements.

In order to undertake drug testing it’s not necessary to comply with the standard, however in a corporate or industrial setting where the outcome of test results could end up being disputed in a court of law, it is highly advisable to select a screening service provider that is certified as being compliant in this standard. Accreditation is provided by the National Association of Testing Authorities (NATA) and further details can be found here.

Drug Test Direct’s complete range of drug tests comply with this standard and the cut-off levels are provided above for your convenience.

Adulteration Testing

Adulterant testing is undertaken in order to test and confirm the integrity or validity of a urine specimen. The various components of an adulteration test have been selected to provide information on the potential adulteration of urine samples that are submitted for drugs of abuse urine testing. It goes without saying that when undertaking screening for drugs of abuse, it is paramount to be assured of the quality and integrity of a specimen, which makes adulteration testing highly advisable.

One of the simplest and most common forms of adulteration is a simple dilution of the urine and other tests such as specific gravity and creatinine can assist in the determination of popular methods in beating drug tests such as dilution or adulteration with bleach, vinegar, sodium bicarbonate, soft drinks or hydrogen peroxide. Since it became possible to detect these common adulterants a market has developed for commercially available adulterants, for which checks such as aldehyde (glutaraldehyde) concentration may be performed in order to determine if a confirmatory drug test is necessary.

Drug Tests Direct is pleased to offer an adulteration test strip capable of testing for all of these adulteration scenarios and more. In addition our popular CupScan II integrates two common adulterants, pH and creatinine, directly into the test. Furthermore, all of our cup products also feature a temperature strip to provide added visual assurance that a fresh sample is being submitted.

Finally, if adulteration is a concern it may be appropriate to test an alternative sample, such as saliva, which it is possible to do using Drug Test Direct’s OralScan product.