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From: Dr P
Password: orange
Date: 14 Apr 2008
Time: 07:04:31 -0700
Remote Name: 64.123.122.2
I agree with Dr Swotinsky about the multiple specimen issue. I'm running into more and more of these situations as employers are doing what Dr Sherman is asking about. As best as I can tell, the cases I've seen are either differences due to dilution or due to someone bringing in enough of something to try to beat one test but failing to have enough to thwart the second test. Most companies are doing the screening on-site test first (contrary to DOT policy of doing the DOT test prior to any non-DOT test). Also, see the Jan 2008 Mayo Clinic Proceedings article, Urine Drug Screening - Practical Guide for Clinicians. While I'd take exception to some of the semantics I like the list of medications that can result in a screening presumptive positive yet a confirmed negative test. Looking at the list there are numerous common medications that could cross react on the screening portion (on-site test). My experience is that very few people, including physicians not involved in drug testing, understand the issue of cross reactivity . Employers who have little or no knowledge of this can put undue pressure on innocent employees and create major problems for themselves. I've heard of HR managers or supervisors quizzing the employee about their medication/drug use. I think this is inappropriate. Also most are not sending the on-site presumptive positive sample to the lab. This is also inappropriate. They rely on the DOT test done later and wonder why there is a difference in results. Lab only testing removes the risk of misinterpretation of the on-site presumptive test since only the confirmed result is divulged (hopefully to a MRO who can ferret out other legitimate medication issues).