These are screening tests with limitations of sensitivity and specificity (potential false negatives and positives respectively) and are NOT intended for medico-legal use. A positive result is reported if the concentration exceeds the clinical thresholds as defined by the national external quality assurance programme for drugs of abuse, which are far less stringent than workplace standards (see table below).
The sample should have a creatinine concentration of greater than 2 mmol/L to qualify as urine.
Methadone metabolites are NOT detectable by this method.
Intentional contamination with soap, salt, vinegar, etc. will interfere with the assay, and dilution with water will tend to produce negative results.
The standard panel includes:
Cannabinoids is available as a separate test – please request this separately if this is required. Only one sample is required for both the standard panel and cannabinoids. Please indicate which tests are required on the request form
SENSITIVITIES OF URINE SCREENING AND CONFIRMATION TESTS FOR DRUGS OF ABUSE
At concentrations below the limit of detection, the drug (or metabolite) will not normally be detected by the usual screening procedure.
A result reported as ‘positive’ in a screening test implies that the concentration of drug present is in excess of the limit given here.
Note that the sensitivity of drug detection will be reduced in dilute urine specimens.
|DRUG CLASS||LIMIT OF DETECTION OF SCREENING TEST||CLINICAL THRESHOLD|
|Amphetamines||1000 µg/L||1000 ug/L|
|Benzodiazepines||300 µg/L||300 ug/L|
|Cannabinoids||50 µg/L||65 ug/L|
|Cocaine (metabolite)||300 µg/L||300 ug/L|
|Methadone||300 µg/L||500 ug/L|
|Morphine||300 µg/L||1000 ug/L|
The duty biochemist may be contacted if you have a query relating to cross reactivity of other drugs in the assay. ext 2935
None. Results reported as “Positive” or “Negative”
Abuse and Compliance (methadone)
4 days (urgent requests can be processed the same day following contact with the laboratory)
Can be added on to an existing request up to 4 days following sample receipt
Please note this test is not UKAS accreditedSpecimen Labelling Procedure