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Q: My son was drug tested and found positive for methamphetamine. He takes prescription methylphenidate. He was told that methylphenidate will not test positive for methamphetamine, and it will only test positive for amphetamine. Is this true?

A: According to several sources methylphenidate (Ritalin) can cause false positives on urine screens for amphetamine, but we have been unable to find any definitive information regarding whether methylphenidate is known to cause a false-positive for methamphetamine on any current urine screen. (Law & Shannon, 2002) In any case, a confirmation test should always be conducted using a GC/MS or similar lab technique, which, providing only methylphenidate was ingested, would show that the sample did not reveal evidence of amphetamine or methamphetamine use.

The very first thing everyone needs to know about drug testing is to differentiate between 'screen' or 'field' tests and laboratory analysis. The 'screen' type tests (stick, cup, strip, color change test, etc.) must not be considered positive confirmation of drug use and need to be confirmed by a drug testing lab. As an article from the Mayo Clinic puts it, 'False-positive results [... from urine screens] can lead to serious medical or social consequences if results are not confirmed by secondary analysis, such as gas chromatography-mass spectrometry.' (Moeller et al., 2008)

The questions to ask when a drug test yields a positive result are:
  • What is the exact type and brand of the screen?
  • Was a confirming test performed in a lab?
  • What chemical exactly was detected? Was it the chemical itself or was it a metabolite the test confirmed?
  • Was chain of custody maintained? Is there a complete record available of the chain of custody transfers?
If the results are important (as they often are) and you feel strongly that the results are in error, ask if you can see the actual lab result documentation, if you can pay to have another lab re-test the same sample, and if there is any way to verify the sample is from your son.

References

Asked By : kat
Answered By : Jon, Doc Willi, Earth
Edited By : Spoon
Published Date : 9 / 24 / 2010
Last Edited Date : 9 / 23 / 2010
Question ID : 3134

Categories: [ Drug Testing ]




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