Urine Drug Screening

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Urine drug screening
Factors affecting a valid specimen
Urine creatinine concentration is assayed to detect diluted
specimens. This can be caused by surreptitious addition
of tap water or excessive fluid intake before the collection. A urine creatinine level < 1.76 mmol/L indicates a dilute specimen. A repeat specimen should be considered.
The temperature of the specimen indicates if it is freshly
passed. If the specimen is fresh, the temperature should
fall in the range of 33–38°C. If the temperature is not in this range, specimen substitution should be suspected.
Adulteration can affect the final results. Smell, visual, and automated checks are performed to check for these
possibilities.
Factors affecting detection time
• Usage pattern
• Drug and dose of drug used
• Urine concentration
• Assay method and cut-off value used
Storage time
• Chain-of-custody samples with positive results: 3 months • Chain-of-custody samples with negative results: 1 month
• All non-Chain-of-custody samples: 1 month
Confirmation
Where confirmation by Gas Chromatography/Mass
Spectrometry (GC/MS) is required (e.g. if results are to be
used as medico-legal evidence in court), specimens are
sent to another Sonic laboratory.
Chain-of-custody
As we are a NATA-accredited laboratory, our specimens
are processed as per NATA requirements.
Results are confidential.
We do not witness specimen collection, but collections at
our collection centres are supervised, and urine temperature is taken immediately after collection. Chain-of-custody forms are completed and specimens are sealed.
Cut-off values
Cut-off values used are as recommended in Australian
Standard AS/NZ 4308-2008

The Test
How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?
How is it used?
Analysis of urine specimens for drugs of abuse only gives information about current or recent drug usage. A urine specimen taken more than 2-3 days after a period of 'drug abuse' is likely to be negative on screening for most substances. Cannabis is the notable exception to this, and can remain at detectable concentrations in urine for 2 weeks.

The approximate detection times for some drugs of abuse are listed below. There is a lot of variation from one individual to another and detection will depend on the dose administered, the frequency and route of administration, the concentration of the urine and the speed at which the drug is broken down and removed from the body.

Drug Length of time it can
be detected in urine
Alcohol up to 1 day
Amphetamines & Ecstasy 1-3 days
Barbiturates 1-3 days
Benzodiazepines 1-3 days
Cannabis (THC) up to 2 weeks
Cocaine 1-3 days
Codeine 1-2 days
Dihydrocodeine 1-2 days
Heroin (morphine) up to 1 day
Methadone 1-3 days

Drugs of abuse can also be detected in other body fluids such as saliva but with saliva the period of detection is considerably shorter than in urine.

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When is it requested?
To detect or exclude the presence of abused and/or illegal drugs. This may be carried out for a number of reasons including a pre-employment screen or to comply with a drug rehabilitation programme.

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What does the test result mean?

A result reported as 'positive' in a screening test implies that the concentration of drug present is greater than a specified cut-off concentration for that particular drug. Australian laboratories use the same concentration to define a positive result and conform to the Australian Standard AS4308 guidelines.

The sensitivity of drug detection will be reduced in dilute urine specimens. At concentrations below the cut-off limit, the drug will normally be reported as not detected.

Drug & Alcohol Testing

Employee drug testing is increasingly being carried out by organisations due to the general recognition that the use of alcohol and other recreational drugs can...
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